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![[Nevada relief map]](nv-br-crater-relief.png "Nevada relief map showing location of impact crater at Black Rock Desert")
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This page presents evidence that an elliptical-shaped impact crater approximately 30 miles (48 km) wide east-to-west and 40 miles (64 km) long north-to-south exists at the Black Rock Desert in northwestern Nevada. The approximate center is at 40.984045 N, 118.916016 W. The center-line of the ellipse is angled toward about 341 degrees at the top or 161 degrees at the bottom, relative to true north.
The crater is heavily eroded. The east and west arms of the Black Rock Desert run through it. Even standing within it, one can't see the crater without knowing which mountain ranges are remaining parts of the rim, floor and central uplift structure.
The Black Rock Desert region appears to be in the middle of nowhere. Yet this is anything but a place where no one has been. The first Americans to record discovery of the Black Rock Desert in 1843 were explorers John C Fremont and Kit Carson. Fremont went on to serve as a Civil War general, US Senator for California, unsuccessful candidate for President, and territorial governor of Arizona. Cities and mountains across California, Nevada, New Mexico and Colorado are named for Carson, including Nevada's capital.
Three pioneer wagon trails bound for California and Oregon went through the Black Rock Desert. The Lassen and Nobles Trails used Black Rock as an alternative to the dangerous high-elevation crossing of the Sierra Nevada Mountains at Donner Pass to California. The Applegate Trail used it as an alternative to the deadly hazardous Columbia River Gorge route to Oregon. That brought tens of thousands and their livestock through Black Rock, who probably experienced no less danger or hardship by this route. Remains of a covered wagon can still be seen today at Black Rock Hot Springs. Like most of Nevada, the area has been thoroughly searched for precious minerals by miners. Eventually the Western Pacific Railroad (now part of Union Pacific) traversed the area on the east side of the dry lakebed, which continues to carry freight traffic day and night.
Today the flat expanse and surrounding mountains of the Black Rock Desert are a common recreational area for rocketry hobbyists, land sailors, rock hounds, 4x4s and campers. Movies, TV commercials and music videos have been shot on the surreal-looking flat lakebed. It is the site of the annual Burning Man festival (which is held about 10 miles southwest of the impact crater outline.) It was where the supersonic land speed record was set in 1997. It was the launch site of the first amateur rockets above 50 miles in 1996 and to space (reaching 72 miles, well above the 62 miles/100km required to claim a space flight) in 2004.
The east arm of the Black Rock Desert, consisting of the winding course where the Quinn River sinks into the mud and sand, is an area mostly under federal Wilderness protection since 2000.
The flat west arm of the Black Rock Desert is passable to vehicle traffic when dry, approximately from May to November, but not immediately after any rainfall. Summer thunderstorms may cause small areas of heavy rainfall, especially in August and September. Reports say that the lakebed is also passable when frozen around January and February. Though I haven't tried it in Winter. During the Spring runoff, a lake usually forms on the Black Rock Desert, but not in the smaller lakebeds in the mountains. The brief formation of a surface lake re-flattens the lakebed.
The entire Black Rock Desert lakebed is on federal land managed by the Department of the Interior's Bureau of Land Management (BLM), from the field offices and ranger stations in Winnemucca, Nevada and Cedarville, California. It's within the Black Rock Desert - High Rock Canyon Emigrant Trails National Conservation Area (NCA). Some areas are federally-designated Wilderness (with an upper-case W) areas, in which BLM Wilderness Rules (basically prohibiting motorized vehicles) apply. However, it is accurate to describe the entire region as a wilderness (with a lower-case w).
This has been a volunteer project for all involved. As best I can, I've tried to credit everyone who has had a role in this. Any omissions are unintentional - please let me know if there are any. There's obviously been a lot of information to bring together here.
An additional purpose of this page is to assist those who will take the research beyond these initial findings. This is just a page on a personal web site, a preliminary finding by amateurs. It does not claim to be a published article in a scientific journal. Some may disagree with the choice of wording to call this a "discovery" before it is published in their favorite membership-only journal. I think there's more than enough supporting evidence to call it a discovery, so much so that someone had to notice it soon one way or another. My intent is that the information here should help interested parties to perform their own verification of these findings and publish where they believe it's appropriate.
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| A view of the near and far rims of the crater, as seen from the CSXT avionics re-entry landing site in the Granite Range. This was originally intended only to show the distance to the Black Rock playa where the rocket was launched. In the lower left is a video documentary cameraman. Photo by Stratofox member Ian Kluft. |
In August 2003, Stratofox members went on a training mission to familiarize ourselves with the Black Rock Range in preparation for searching for the landing sites of space rockets there. A camp site was chosen at the Upper High Dry Lakebed in the southern Black Rock Range, from which exploration of the area was done.
Most of the members on that trip had little or no interest in Geology. My background included just some junior college courses and field trips on volcanoes years earlier while residing in Mount Shasta City, California. (Mount Shasta is one of the major volcanoes of the Cascade Range.)
I noticed that the igneous rocks on top of the mountains surrounding Upper High Dry made it look like it must be a volcano. But it looked very strange for a volcano because there were many non-igneous rocks lower down on the same mountains. That remained an unanswered curiosity for a few years. It was easy to brush off something strange about the area after driving over 30 miles on the already-strange-looking dry lakebed to get there. It's easy to accept that the entire region looks surreal.
In September 2003, Paragon Astronautics attempted the launch of its Dragoon II rocket for a suborbital space flight. On that attempt, each of the launch windows passed without being able to launch the rocket, in most cases for weather. Each time, Stratofox assisted with verifying that the downrange areas were clear of people, usually including by overflight in aircraft owned and piloted by Ben Woodard and Ken Samuelson. Aerial photos of the area by Rafael Skodlar later turned out very useful in researching the theory of the impact crater.
In May 2004, CSXT succeeded in the first amateur rocket launch to space, reaching 72 miles in altitude. 62 miles (100 km) is the minimum required to claim a space flight. It landed 30 miles from the launch site as intended. However, the rocket nudged its own launch rail so it landed in the Granite Range instead of the Black Rock Range. From the landing site at 6600' elevation, a photo of the distant Black Rock Desert playa was later identified as showing the near and far rims of the crater.
Paragon's Dragoon II did eventually launch in June 2004. It was not successful in reaching space. Another attempt dubbed Dragoon IIB was made in September 2005, which also failed to reach space. This goes to show that Rocket Science really can be as difficult as its reputation says.
In September 2006, having liked visiting the area for its remoteness and surreal beauty, Stratofox members returned to Upper High Dry Lakebed on a recreational campout. Three of the group, Sean Lynch, Nate Dietrich and Brian Nelson went rock climbing on the "island" in the dry lakebed. They observed that the rocks were so "crumbly" and fractured that there was absolutely nowhere to safely anchor their climbing gear. Nate had to drive his 4x4 pickup truck on top of the island to provide a safe anchor. When the rest of us returned from visiting the nearby "confluence point" of 41.0 degrees north latitude and 119.0 degrees west longitude, we took pictures of our friends climbing on the rocks. To me, the deep fracturing of the rocks in the island became yet another point of suspicion that was strange for a volcano.
About a week before that trip, the idea had occurred to me to look for indications of an impact crater, in addition to volcanic origins. The idea came to mind because there are three somewhat circular geographic structures in the southern Black Rock Range - at Upper and Lower High Dry Lakebeds and a semicircular ring which makes a hook shape in the southeastern corner of the Black Rock Range. Though not having experience with impact craters, at the time it was just another idea about the area that didn't make sense either.
I quickly found out that the only hard evidence big enough to find in a photograph of the outdoors is a shatter cone. And looking at photos of the rocks on the island, there were some 30-foot tall somewhat conical structures on them. They didn't look anything like the "horse-tail" patterns shown in examples on the Internet.
An online article titled "Shatter cones: Branched, rapid fractures formed by shock impact" by Sagy, Fineberg, and Reches (see references) showed that shatter cones can look very different depending on the hardness of the rock when the intense shock wave travels through. Like the cone of a sonic shock from a rocket or aircraft traveling in air, the impact shock travels through bedrocks leaving fractures in conical patterns behind parts of the rock that disturb it. The paper indicated that many shatter cones were observed starting at fractures perpendicular to the direction of the shock's travel. And for harder rocks, the examples did look like the rocks at Upper High Dry. It showed that shatter cones happen on large and small scales like a fractal - smaller cones are found inside the bigger ones. And that's a requirement for recognizing shatter cones.
I didn't want to jump to conclusions because this would be a huge claim to make, and shouldn't be done without reason for a lot of confidence in it. It took some studying of the photos. The article's observation that shatter cones often start at perpendicular fractures was the breakthrough in recognizing them. Once I found some, they were everywhere. It was like spotting your first alligator in Florida - and then looking around again only to realize how many there are. The cones matched the required criteria of being present on large and small scales. Though the rocks are eroded and it's hard to recognize.
When I brought this to the Stratofox team, initially the reaction was silence. One member who is actually a space scientist for his day job eventually said it didn't look like any shatter cones he had ever seen. And that seemed like the end of that.
Besides the skeptical reaction,
others mentioned they just didn't have any experience in this area
but were interested how it turns out.
I realized I wasn't the first to experience this.
I read stories online that others proposing the discovery of impact
craters had met with intense skepticism.
Even the TV documentary showed lengths that Shoemaker had to go to in
convincing his fellow geologists.
It turned out to be a "blessing in disguise". If the shatter cones really were proof of an impact, then there was no harm in calling them circumstantial evidence. There would have to be more evidence. I just didn't know if it would be within my means to find it. The search for information that followed would put together a convincing case based on circumstantial evidence alone, and more items that are arguably proof as well.
I noticed on wide zoomed-out satellite imagery at Google Maps that the mountains across the Black Rock playa to the east and south make a semicircular pattern. Features on the valley floor visibly follow them in a concentric pattern. They're also concentric with the semicircular ring that makes the hooked southeast tip of the Black Rock Range.
That seemed like too much to ask everyone else to believe. It would mean the estimate of the crater was over 25 miles across, encompassing much of the Black Rock Desert region. I didn't mention this "wider crater" idea for a few days. I needed to look at it some more myself first.
I followed up on advice from Rafael Skodlar and Bryan Klofas to look up government data on the region. As it turns out, the Nevada Bureau of Mines and Geology (NBMG) at University of Nevada, Reno (UNR) has online scanned documents from many mining sites. These remain in image format - there has been no optical character recognition to extract text from them - so they can't be found with a regular Internet search engine.
Of high interest to me were ones from the area around Sulphur, the name of a ghost town, a railroad siding track and some large open-cut mines. As I'll describe below in the "Sulphur Group Layers and Camel Conglomerate", a mining geologist's 1980 description of some rock layers presented a geological mystery at the Sulphur Mining District. He found rock layers containing altered rocks which the source of alteration couldn't be identified. But it read exactly like the layers of ejecta outside an impact crater.
That was the breakthrough I needed. So there was an unsolved local mystery at Sulphur which sounded like an ejecta layer. The wider crater idea wasn't necessarily nonsense after all.
When Brad Douglas volunteered to help with the research, he was the first to whom I mentioned the wider crater theory. He studied with a minor in Geology in college. He offered to use his experience with the Open Source GRASS GIS software to see if multispectral satellite imagery and radar data could shed any light on the story. He confirmed that within the outline of the wider crater, the geology is different from the rest of northwestern Nevada. (See below in "Unusual geology within elliptical area".)
Using photos from past years by several Stratofox members, Rafael Skodlar, Sean Lynch and myself, I was able to determine that the observation from the Sulphur Mining District of red igneous (thought by the geologist to be rhyolite lava) dikes in a white breccia rock layer is something found thinly across the crater floor, and in much thicker layers in the crater rim.
Another interesting find at NBMG was a masters thesis from 1980 which talks about the "Soldier Meadows Tuff". This time the information refers to the north side of the crater outline. The rock layers sounded just like at Sulphur, and match the expected sequence of impact ejecta. The Geology student and papers referenced by him found evidence that the massive Soldier Meadows Tuff layers were deposited as a single cooling unit, so they came from a single eruptive event. More will be presented about this below. But it was another geological mystery in the area which turned out to offer support for the crater discovery.
With that, we found enough online. We needed to go back and visit Black Rock.
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| At a stop on Soldier Meadows Road during the January 2007 expedition to investigate the impact crater. photo by Dave Brock |
The following people (listed with their Amateur Radio callsigns) participated:
Based on descriptions of the rock layers at Sulphur and the Soldier Meadows Tuff, Brad and I both expected we'd be able to find rocks with impact shock effects at or below the white breccia rock layer which spans the crater area. Mindful of federal Wilderness areas which have vehicular travel prohibitions, we visited two sites where we could reach the white layer.
We didn't even attempt to reach the Black Rock Range because of uncertainty over the surface of the Black Rock Desert lakebed. It's usually muddy this time of year in a way that you won't get your vehicle out until Spring. Access to the Black Rock Range often has to wait until around June or July.
Photos from the trip and of rocks collected are at http://www.stratofox.org/pics/sca1-20070128/ . Among the rocks collected, we found an excellent sample of "horse tail" shatter cones, and numerous other samples of apparent shocked quartz. More on this is below in the observations section.
A few pieces of evidence appear that they will constitute positive proof all on their own when confirmed by experts. All of these are results of shock effects on rocks. There are some pressures which can't be achieved even by the meanest volcano. Things like shatter cones or shocked minerals can only happen in either a nuclear explosion or an impact event.
I'm assuming, but it's a safe assumption, that we can rule out a nuclear explosion in northern Nevada. Therefore, the discovery of any shatter cones or shocked minerals would logically be proof of an impact event.
Though the erosion that created the Black Rock Desert lakebed removed large portions of the crater rim, where it remains, there are the largest white and red layers of ejecta facing inward.
Brad Douglas noticed that the current USGS maps showing the trace of the Black Rock Fault, partly as an assumption based on the cliff walls of the Black Rock Range, turns east-west within the outline of the crater. But there are no east-west faults anywhere else around Black Rock.
Brad is preparing maps of the area based on satellite imagery at various infrared wavelengths. He's still working on the maps so they aren't available yet. But he says he sees the area within the crater stands out as different from the surrounding region with values that indicate much higher levels of "Nickel, Copper, Iron and Mafic igneous rocks." The heat of impact melts and vaporizes most of the impactor, leaving it as a constituent of the remaining melt rocks in the crater.
The presence of high levels of Nickel and Iron may be suggestive of favoring a nickel-iron asteroid over a comet for the impactor. I'm surprised we've been able to find this kind of information before turning it over to the Geology community. I didn't expect to have any evidence about the impactor.
Though it's outside the scope of this topic, I wonder if Brad has discovered a new technique for analysis and discovery of impact craters.
| Shatter cones on the island: How did this point do? |
Wrong!
Corrections accepted |
While the apparent structure to the fractures in these rocks might not rule out being fractured basement rocks within a crater, these are not shatter cones. |
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| Shatter cones in the January sample rock: How did this point do? |
Wrong!
Corrections accepted |
It's intruguing, and a reason to keep looking around the area. But experts who looked at the photo say it isn't convincing as a shatter cone. It isn't necessarily completely wrong - I found rocks with exactly this same pattern along the highway at Sierra Madera in Texas, which was confirmed as an impact site decades ago. |
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| A rock with shatter cones which was most likely collected from near the Little Joe Opal Mine, but maybe from NE of Sulphur. (My fault for not recording the location.) photo by Brad Douglas |
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| A close-up of some of the shatter cones. photo by Brad Douglas |
A shatter cone is caused by the pressure of the impact shock passing through
pre-impact bedrock and leaving fractures as it passes through.
The process leaves conical fractures on large and small scales.
This is considered positive proof of an impact because it takes more
pressure than a volcano can produce.
Shatter cones are also produced in nuclear explosions,
though we can safely eliminate that as a possibility in northern Nevada.
We found shatter cones on a rock collected on the January 28 expedition. I have to admit to improperly collecting this one so I don't know with 100% certainty where it was picked up. It was at one of the two sites we visited that day, either near Little Joe Opal Mine or the abandoned mining site NE of Sulphur. I remember I was hiking following Brad up the hill when I picked it up. So that's most likely at the Little Joe site. I saw a colorful rock that got my attention. Since it was sitting loose, not "in-situ" part of a fixed rock formation, I didn't expect it to be of any use for geology purposes. Since it looked interesting with its colors, I put it in my jacket pocket without a chance to give it another look. When we got back, Brad was the one who took a closer look and noticed that it has shatter cones.
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| Zoomed-in view of Stratofox participants climbing on rocks at Upper High Dry. |
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| Zoomed-in view of Stratofox participants climbing on rocks at Upper High Dry, with annotations showing conical structures in the rocks. |
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| Zoomed-out view of Stratofox participants climbing on rocks at Upper High Dry. | |
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| Zoomed-out view of Stratofox participants climbing on rocks at Upper High Dry, with annotations showing conical structures in the rocks. | |
| download high resolution image of the island view shown above (3Kx2K) 3.4MB JPEG | |
| These are the original eroded shatter cones that got the research into an impact crater at Black Rock started. The photo is of Stratofox members Sean Lynch and Nate Dietrich observing Brian Nelson rappelling on the "island" at Little High Dry Lakebed in September 2006. photo, croppings, scalings and annotations by Ian Kluft |
The shatter cones at Upper High Dry have no problem about being in-situ.
They're so big that they're not going anywhere.
The problem they have is that they're so eroded that they weren't
really recognizable as shatter cones when I showed the photos to others.
Though it would appear any discovery of shatter cones should be proof,
due to the doubt others had about them,
I treated these like circumstantial evidence and went searching
for more evidence.
It turned out to be a good thing.
It has confirmed this is a location where shatter cones could be found.
These look different from the "horse tail" style shatter cones often found on photos on the Web, and on our sample rock from the Little Joe site in the Calico Range. One probable reason is the hardness of the rock. It just fractures differently. Examples of different kinds of shatter cones can be found in "Shatter cones: Branched, rapid fractures formed by shock impact" by Sagy, Fineberg, and Reches (see references) It was from that reference which I realized shatter cones can look different than the horse-tail pattern - some samples from harder rocks looked similar to these.
Conical marks can be found on large and small scales by looking all over the rock faces. The roughly conical-shaped largest rocks in the photos are shatter cones too. This fractal effect with smaller cones inside each larger one is part of the definition of shatter cones and required for verification of them.
Shatter cones are also supposed to point upward and inward toward the center of the impact. Indeed these do. They point upward and slightly to the east, toward the point already identified as the apparent geographic center of the elliptical crater from satellite imagery and topographic maps. Each time there has been a chance to correlate data like this and let the theory sink or swim on its own, it kept swimming. That was even before we had the January 28 expedition and found more shatter cones and apparent shocked quartz.
| Possible shocked quartz: How did this point do? |
Wrong!
Corrections accepted |
The scale is too large to tell one way or another. Even the magnification we had available wasn't enough. This would require a scanning electron microscope. We'll continue to look for help from the experts on that. |
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| A sample from the white rock layer, from near Little Joe Opal Mine. photo by Brad Douglas |
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| Magnified view of apparent shocked quartz in the sample from the white rock layer. photo by Brad Douglas |
There are actually many types of minerals that can show shock effects. Geologists talk about shocked quartz probably because it's the most abundant, as a common mineral, and easiest for them to find with fancy microscopes. For an amateur like me, it's probably all I'll be able to find without that fancy equipment. I'm calling it "apparent" shocked quartz because the real verification is done with a scanning electron microscope. I don't happen to have one lying around the house. (That's a joke. No one does.) But it's easy to see the criss-cross pattern in the crystals in this photo, which is exactly what we were looking for.
Brad took pictures of the rock samples with a macro lens on his digital SLR camera. I found the shocked quartz in one of his photos. So that's either a role reversal or good teamwork compared with how he found shatter cones in a rock I collected. He definitely earned his share of the credit in finding the proof of an impact. His Geology experience has been invaluable in this effort.
As the annotated photo image shows, the quartz crystals have sets of parallel lines, one set at an angle from the other. The perpendicular line may be a fracture or another shock in the crystal - it's hard to tell at this magnification.
Fractures in quartz were extremely easy to find.
The difference in this case was finding the multiple sets of parallel lines.
There are others that we looked at and thought may have shock patterns.
Getting good pictures has been difficult.
I did that. I found there are two documented geological mysteries in the area: the Sulphur Group/Camel Conglomerate and the Soldier Meadows Tuff. Even though these are 40 miles apart, they're both part of the crater ejecta layers.
The Nevada Bureau of Mines & Geology (NBMG) at University of Nevada, Reno has gone to a lot of effort to put scanned images of archived documents online. There's no text so it isn't possible to simply find this stuff with a search engine like Google. But with some information like titles, mining districts and years, it was possible to narrow down this search to areas in and around the outline of the crater. You can look up documents more easily knowing the names of mining districts which are in the vicinity of your research area. I've looked up the mining districts and listed them here in clockwise order by their direction from the center of the crater.
The Nevada mining districts which include parts of the crater and rim are
In all of the cases below, local geologists had almost enough of the picture to make this discovery themselves. In 1980, it was probably too early - Geologists just didn't get impact craters in their education. (Most probably still don't today.) Also, I get the impression that mining Geologists in Nevada have pretty much one thing on their minds - precious minerals. If they don't find any, they mark down their observations and move on.
It looks like it required a different perspective to find this. I didn't notice until I had visited the Black Rock Desert literally 30 times.
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| Breccia dikes occur in numerous rock fractures at an abandoned mining site in the crater rim near Sulphur. photo by Ian Kluft on Jan 28, 2007 |
| Fractures and breccia dikes at Sulphur: How did this point do? |
OK
So far so good |
The photos and local geological literature of the fractures and breccia dikes at Sulphur have ranged in reactions. Some called it intriguing and worth another look. There have been no objections. |
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A 1980 paper on file at NBMG by geologist Andy Wallace,
"Geology of the Sulphur District, Southwestern Humboldt County, Nevada",
found a mystery in a 2000-foot thick group of layers of rocks that
Wallace calls the "Sulphur Group".
One of the layers, the Camel Conglomerate, was named for the nearby
Silver Camel Mine.
Today the same layer is called the Crotoot Conglomerate by Vista Gold Corp.
For this writing, I'll stick with the older name because it sounds better.
A clarification is in order about the location of Sulphur, Nevada. It's obviously named that way because sulfur mining took place there. When I spell it like Sulphur and capitalize it as a proper noun, I'm referring to the vicinity of an adjacent ghost town and railroad siding track which each bear the name Sulphur. The Sulphur Mining District covers mines in the Kamma Mountains near the railroad siding at Sulphur, no matter whether they're mining gold, silver, mercury or sulfur, all of which have been tried there.
So when Wallace referred to the Sulphur Group of rock layers, he was talking about rocks observed in the Sulphur area, not a reference to the element sulfur.
Wallace's mystery was what could have produced these rock layers he found. The bedrock, or Kamma Mountains Group, is old basalt lavas.
Wallace's hypothesis asks the reader to believe that the entire region became a boiling vat of acid, and uniformly cooked all the rocks in that layer (and no other layers above or below them) very evenly across the region. It probably wasn't a bad guess for 1980. In Wallace's credit, he lists his observations in sufficient detail to allow readers 27 years later to glean a lot of information from it. His papers were the most useful of any I found for the NBMG Sulphur Mining District.
The evidence of an impact crater sheds new light on this. The heat and pressure of a meteor impact can and does alter rocks, all across the scale up to melting them. It would also dump layers of ejecta in and around the crater. They'd be relatively uniform because they came down all at once in a single event. Wallace's observations at Sulphur sound completely consistent with the ejecta from a large impact.
Among countless useful information in the "Traces of Catastrophe" book (see references), there is a part which applies particularly well to these observations at Sulphur. n Page 98 (109 in the full e-book PDF file):
"A few impact structures have been so deeply eroded that no distinctive circular feature remains. Such structures exist only as patchy remnants of unusual "volcanic" breccias and other deformed rocks, and in many cases [e.g., Rochechouart (France), Gardnos (Norway)] the shock effects (e.g., shatter cones, PDFs in quartz) were only identified in the rocks decades after the rocks themselves had been first described. The accumulated geological literature, especially papers that describe strange breccias and unusual "volcanic" rocks, may be a rewarding ground in which to search for unrecognized impact structures of this kind."(Note that when the geologist refers to "PDFs", it means "planar deformation features". It's just a coincidence that the quote occurs in a Portable Document Format file. Both use the same abbreviation.)
On Page 78 (Page 89 in the full e-book PDF file), there is a description of layering of ejecta from some known craters.
In large impact structures, the ejecta deposits preserved outside the crater contain a recognizable sequence of different lithologies. The sequence at the Ries Crater (Germany) (see von Engelhardt, 1990, 1997, and references therein) contains a lower unit of polymict lithic melt-free breccia (Bunte Breccia) overlain by melt-bearing breccia (suevite). Some of the ejecta at the Ries also occurs as large (tens to hundreds of meters in size) limestone blocks ejected intact from the crater and skidded for many kilometers across the surrounding ground surface (von Engelhardt, 1990, pp. 264-265).
This has has direct similarities to the Sulphur Group layers.
The lowest layer is fragmented portions of rocks ("volcanic clasts")
from the Kamma Mountain layers below,
with no indications of melts.
The Sulphur Group including the Camel Conglomerate contain layers
which sound similar to the layers of melt-free breccia overlain
by melt-bearing breccia, which would correspond to the Camel Conglomerate
and the white breccia layer.
Edmund J Stuart's masters thesis,
"Distribution of Uranium and Associated Elements in the Soldier Meadows Tuff,
Northwestern Nevada"
(see references)
calls upon earlier research in the region and personal communication
with researchers in the area to describe a picture of the Soldier Meadows Tuff.
There is a specific location called Soldier Meadows, where an active ranch and remote-setting bed & breakfast operates today. This was originally settled as the US Army's Fort McGarry when the Applegate and Lassen pioneer wagon trails came through the area.
However, the Soldier Meadows Tuff covers a much larger area surrounding the rim of the crater from the northwest to the north, as far away as Summit Lake.
The most notable observation is that all the layers of the Soldier Meadows Tuff were determined to be a single cooling unit, meaning the enormous amount of material in all the layers came down in one event. Yet there is no volcanic caldera which produced this apparent eruption. While a previous author cited by Stuart (Korringa 1973) estimated the location of a probable "linear vent" area along a fault line, no volcano was identified in the area. So that was an ongoing mystery.
Some past theories about the Soldier Meadows Tuff which were found on the Internet, since it's such a large formation, included a possible past location for the Yellowstone Hot Spot tens or hundreds of millions of years ago. But even there, they listed a question mark next to the Soldier Meadows Tuff. Other researchers appear to have connected the lines of old calderas from Yellowstone to the Newberry Crater in Oregon, leaving northwestern Nevada out of that picture. But it was important to check alternatives.
Indeed, the hot spot was Brad's primary alternative theory until we found the Hycroft mine fault diagram and the shatter cones on a rock sample on Jan 31.
However, I found Stuart's thesis on Jan 22. It made an excellent comparison of the opposite sides of the crater before the Jan 28 expedition to the area. The layers that Stuart describes are similar to what Wallace found at Sulphur.
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| This faulting diagram from the public disclosure of the Hycroft Mine (see references) by Vista Gold Corp shows faulting from apparent terrace collapses in the rim. A complex rim structure like this is typical of a large impact crater according to "Traces of Catastrophe". |
| Sulphur mining fault diagram: How did this point do? |
OK
So far so good |
This has received among the best response of the evidence presented. It is the right kind of faulting in the right place. |
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When we saw the fault diagrams, it was a jaw-dropping moment. At first one wonders how they didn't notice they had mapped the faults in the wall of a giant impact crater. They did it so well. Like so many other geological documents from the area, an impact crater was obviously just not on their minds when it was prepared. If the idea had even occurred to anyone there, they practically had proof right in front of them.
A note at the bottom of this diagram says it was made in 2002 when the Brimstone Mine (also at Sulphur) was reactivated.
Large craters, more than a few km across according to "Traces of Catastrophe", have terraced collapses around their rims. That's one of the features which differentiates larger complex craters from smaller simpler ones. As these collapses occur, the cracks become inward sloping concentric faults. And that's exactly what we have here in the diagram.
The lower diagram shows a cross section further south
but also at the Hycroft Mine.
The two cross sections show inward-sloping faults
accounting for about 5 or 6 levels of terrace collapses
which occurred in the rim of the crater.
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| A view to the southeast from the top of Black Rock Point looks over the white breccia layer with examples of melt-rock dikes in the white layer like at Sulphur, and possible impact melt above it all. The open-cut mine at Sulphur is visible 15 miles in the background. Photo by Rafael Skodlar during the Stratofox 2 camping/training trip, Aug 23, 2003 |
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| An aerial view of of the Black Rock Range where numerous red melt-rock dikes come up in the white breccia layer just like at Sulphur. Photo by Rafael Skodlar during the Paragon Dragoon II space launch attempt, Sept 16, 2003 |
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| A view from the ground at the "confluence point" of 41.0 N 119.0 W toward the Black Rock Range. Several red melt-rock dikes can be seen coming up in the white breccia layer just like at Sulphur. Photo by Ian Kluft during the Stratofox 3 camping trip, Sept 9, 2006 |
A recurring feature in the white layer is red melt-rock dikes.
These occur where melt rock came down into cracks from above.
Where we see them sticking up,
the melt rock layer above has been eroded away.
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| Stratofox member Bryan Klofas stands by a small cave he found in the Black Rock Range facing toward the east arm of the Black Rock Desert, about a mile east of Upper High Dry lakebed. The overexposed mountains 15 miles in the background are the Kamma Mountains near Sulphur NV. Reviewing the photo again more than 3 years later, I've noticed the rocks transition gradually from breccia (broken up) to a lava-like melt that contains other rocks, none of which is normal for a volcanic site. The breccia rocks on the right resemble other photos from the Net of suevite (pronounced sway'-vite), an impact-generated rock with jumbled fragmentary contents, which does occur in close proximity with melt rocks in the center of a large/complex crater, according to French. By my estimate from the partial ring facing the east arm of the playa on the map, this location could be in the wall of the remainder of an inner uplift ring of the crater. Photo by Ian Kluft on Aug 23, 2003 during the Stratofox 2 camping trip. |
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| Rock seen near Sulphur with graduated melt/nonmelt transition. photo by Ian Kluft on Jan 28, 2007 |
That was one of the first things that got my attention back in 2003. The lava-like appearance of the melt rocks led me to believe it was volcanic. But I've seen volcanoes. Lava flows don't blend into their surroundings - they have rather sharp boundaries, even from older lavas that they come in contact with.
The reason why graduated transitions are possible in an impact site is because the heat and pressure that the rocks are subjected to can vary significantly in a short distance. You're seeing the areas where there was enough heat and pressure to melt the rocks, and areas in the rock where the heat and pressure fell below that level over the range.
Even below the melting point, there are lots of shock effects to observe.
They're anywhere you see these transitions.
These are places that Geologists will look more closely and find
things like impact glass and shocked quartz.
At much lower pressures, shatter cones occur.
All these shock effects are at pressures higher than any volcano can produce.
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Columnar jointing is a rock formation where formerly molten rocks
cooled with vertical fractures. Viewed from above they're in hexagonal
columns or something close to it.
This indicated the rocks had a chance to cool slowly while sitting still in a pool, not flowing. It can happen with volcanic lava rocks, such as at California's Devil's Postpile National Monument. It has been observed with impact melt rocks as well, such as at the Mistastin Lake Crater in Labrador, Canada.
These columnar jointed rocks can be seen at the Black Rock Desert at the
level that used to be the crater floor.
Today the Black Rock playa level is hundreds of feet below where the
crater floor used to be.
Erosion by glaciers and/or streams cut through the crater.
Where the impact melt pools used to be on the crater floor, today
there are rock formations with columnar jointing.
The Black Rock Desert region is a harsh desert environment. People should not venture there without plenty of water and emergency supplies. No one should attempt to travel there alone or in just a single vehicle. At least a second vehicle gives your group a measure of self-rescue capability, which is important.
There is no cell phone service - the only viable long-range communications are Ham Radios and satellite phones. Satellite phones, usually by Globalstar but also more expensively by Iridium, are available for sale or rent at retail locations - the nearest is in Reno. Ham Radio requires an FCC Amateur Radio license, which can be obtained with a written exam that any technically-inclined person can pass with at least a few evenings of study. I founded RadioExam.Org to help people studying to get their Amateur Radio license.
Someone should be aware of your travel plans when you go there, so they can report you missing if you fail to return on time. Some areas of the crater and ejecta field can be more than 60 miles from the nearest paved road. While the area is frequented by 4x4 parties nearly every Summer weekend, it is possible for anyone unprepared who becomes stranded to die before rescue arrives. On a recurring basis, people who go to Black Rock unprepared get stuck and are later found dead. So go prepared - if you can summon a rescue and survive a wait, you'll be fine.
Keep in mind that the nearest major hospital with a trauma center is in Reno, a 2-1/2 hour drive from the middle of the crater. There is a medical clinic and a Washoe County Sheriff's office in the town of Gerlach, both of which are capable of dispatching a medevac helicopter from the Washoe Medical Center in Reno. Bureau of Land Management (BLM) staff have radios which can also summon help.
I encountered some skepticism or wait-and-see reactions initially from friends, much like the stories told by others who have proposed the discovery of an impact structure. But that turned out to be a useful hurdle to jump over. As I searched for more information to convince my friends, the process built a larger body of evidence. As more friends became convinced it was worthwhile to help, even if they weren't yet convinced of the crater, the effort gained momentum. More evidence was discovered.
The result is far better now for it. Rather than just hypothesizing about the meaning of apparent shatter cones in photos from a campsite at Upper High Dry Lakebed, there is enough evidence to make a convincing case from several angles.
So what do we know for sure? The existence of an impact crater at Black Rock is proven circumstantially. (To me, it's beyond doubt based on the weight of the evidence.) Though details about the crater will be the subject of study by Geologists and Geology students for many years to come.
How do we know that? Originally I thought the Upper High Dry shatter cones were proof. But the Jan 28 discovery of another rock with much better defined shatter cones in a "horse-tail" style is likely to be confirmed as proof that the rocks in the area experienced a shock wave worse than any volcano can produce. (Geologists who have looked at the photo say it isn't convincing to them, based on the photos alone. Though there are also negative cones on the reverse side of the rock as the reference by Sagy says there should be. It's OK to wait until they find evidence they're happy with.) Another rock, taken from the white breccia layer, had "apparent" shocked quartz, also a product of an impact shock. I call it apparent because it really needs an electron microscope to officially confirm it. But the image of the criss-cross crystals in the quartz is clear enough to give high confidence it will be confirmed.
Beyond those evidence that an impact shock occurred in the rocks, there is an elliptical area with mountain ranges that still form remnants of a rim, where the geology is different from the Basin & Range region. Brad Douglas says his review of infrared satellite imagery in various wavelengths indicates increased levels of Iron, Nickel and Copper in the impact melt rocks in the crater. Iron and Nickel are typical constituents of asteroids - they would be expected to be found as traces in impact melt rocks exactly where he found them. (Brad's data and sources will be posted when he's done assembling them. He expects that to be later in February.)
The rim as seen on the map has only five mountain ranges which remain of it. Yet going to those places one finds similar layering of rocks which match the expectations of a large crater's rim. The rock layers were already described by geologists at Sulphur and Soldier Meadows in 1980. Those descriptions show, as expected for impact ejecta, the lower layers are mostly material that was blasted out of the crater consisting of bedrock material. As the layers go up, more altered and finally impact melt rocks become predominant. Again, that's as expected - the impact melt is last to leave the crater so it lands on top.
Also significantly, alternative theories of volcanic activity were not able to be substantiated with the location of a volcano in the area which could have produced such volumes of material. The igneous rocks in the area are either very old pre-impact basalt lava bedrock layers or relatively newer impact melt rocks.
The mine at Sulphur also had an unexpected contribution to the research in the fault diagram. It looks so obviously like the rim of a large impact crater, with 6 levels of terrace collapses, that it's hard to believe this has gone undiscovered for so long. But many Geologists before them also had enough information in hand to make this discovery and also missed it. So they're in good company.
So what don't we know about it? A lot. Geologists will want to determine its age. The size of impactor is going to be a question that will interest the general public. It has only been six weeks since the research effort began. Answering some questions has created many, many more.
Based on advice from e-mail conversations with Bob Verish, this will be submitted to the Impact Field Studies Group (IFSG) for inclusion in their Suspected Earth Impact Sites (SEIS) list. Their web site says SEIS entries are usually entered with a low confidence ranking until IFSG members have visited the site and done their own analysis. That sounds like a reasonable approach because this web page only begins the process where Geologists will determine how they wish to pursue it. This isn't what any scientist would consider a published work. It is however hoped this page will be useful in its intent to provide enough information for others to verify it for themselves.
In the local area, this will also be sent to the Geology Dept at University of Nevada, Reno.
Update 12 Feb, 2007: IFSG is adding this to the SEIS list. The next update will be posted in April. Note: this is not an endorsement by IFSG - they're just saying they'll keep it on the list to take a look at it. The initial listing (in the style of notes that will be inserted in a table) provided by David Rajmon is as follows:
Elliptic pattern of the surrounding mountains (tops defining the diameter). Multispectral satellite imagery shows that the inside of the structure stands out of the surrounding geology, indicating indicating increased levels of mafic igneous rocks, Ni, Cu, Fe. The central area of the structure (Black Rock Point) displays common centimeter to meter scaled features interpreted as possible eroded shatter cones (Kluft, 2007). The rim of the proposed structure hosts 1) a 300 m thick red conglomerate with coarse volcanic clasts (many from basalt Kamma Mountains Group, 2) "Camel conglomerate" with slate, siltstone, milky quartz and occasional limestone fragments fining upward and containing more volcanic fragments upward, and 3) white breccia of mostly altered "volcanic" rocks (Wallace, 1980 in Kluft, 2007). Soldier Meadows Tuff surrounding the rim in the northwest to north was interpreted as a single-event deposit without know volcanic source (Stuart, 1980 in Kluft, 2007) These rocks could represent ejecta.Three sets of planar fractures in quartz with fracture spacing 0.5-1 mm were observed on photographs of a hand sample from Calico Range. Single sets of fractures in quartz are common. Melt lava-like rocks blend into unmelted rocks and could represent impact melt. Unnamed igneous rock formation at Black Rock Desert, Nevada between Trego and Sulphur with columnar jointing could represent impact melt sheet. Hycroft Mine at Sulphur shows normal faults dipping west, consistent with this being a possible impact structure eastern wall setting (Kluft, 2007).
Comment from D. Rajmon: Although the above observations are consistent with impact scenario, they are also consistent with a volcanic scenario and the normal faulting could just be the result of the Basin and Range extension. The reported shatter cones do not appear convincing on the pictures. Nevertheless, if this is an impact site, there appears enough material preserved that should contain wide range of shock indicators.
References:
Kluft, Ian (2007) Submitted for Study: Discovery of an Impact Crater at Nevada's Black Rock Desert. (online, published on 10 Feb 2007) http://ian.kluft.com/blackrock/impact-crater/
Stuart, Edmund J. (1980) Distribution of Uranium and Associated Elements in the Soldier Meadow Tuff, Northwestern Nevada. Masters Thesis, Michigan Technological University, http://www.nbmg.unr.edu/scans/0080/00800038.pdf
Wallace, Andy (1980) Geology of the Sulphur District, Southwestern Humboldt County, Nevada. Nevada Bureau of Mines & Geology (NBMG), http://www.nbmg.unr.edu/scans/4680/46800011.pdf
The SEIS listing sounds fine to me. Bear in mind that there was never any chance that a scientist could look at this web page and say, "Oh, you're right", or anything sounding like an endorsement. I knew they would have to look at it themselves. For a report submitted from amateurs to professionals, I think this was a very good start. Since it's now likely to be investigated, it's an understatement to say I'm satisfied with the result.
Thanks to Rafael Skodlar for offering permission to use his photos in this effort even before I knew how much I needed them. As it turns out, he took high resolution digital photos in 2003 in just about all the places I wanted to have pictures now in 2007. (I didn't have my own high-res digital camera until 2004.)
Thanks to Bryan Klofas for finding the invaluable "Traces of Catastrophe" reference on the web. (And thanks to Dr Bevan M French for writing it!)
Thanks to Heather Stern for helping with researching online Nevada geology documents.
Thanks to the members of the Stratofox Aerospace Tracking Team for their support and patience in the search for more evidence.
Thanks to these people who showed confidence in my theory and participated in the Jan 27-28 trip to Black Rock to investigate the crater: John and Donna Ballard, Dave Brock, Brad Douglas, Pierce Nichols, and Heather Stern. Thanks to all who wanted to come and tried to make arrangements in their schedules, including Dave Goodin, Dave Masten and Sean Lynch.
Thanks to Mark Whittington who acted as the Stratofox Point of Contact for the Jan 27-28 trip to Black Rock. He was ready to call for assistance if we didn't check in on schedule, and passed along our reports to the team.
Thanks to the Civilian Space eXploration Team and Paragon Astronautics, whose competition for the first amateur rocket launch to space sent Stratofox on a training expedition to prepare to look for each of their rockets in the Black Rock Range. The volume of Stratofox members' photos taken there because of those events led to having a large pool of photographic data to review now for clues of impact crater geology.
Additional thanks for making the online research so fruitful...
All computations performed in this research were done on computers running the Linux operating System.
| Feb 12, 2007 | Added text from Suspected Earth Impact Sites (SEIS) listing to Where to go next. Also added links to Rocketry Forum and Dick's Rocket Dungeon blog to Where People are Talking About It. |
| Feb 14, 2007 |
At the request of Brad Douglas, I have changed the title of the web page to
"Submitted for Study: Discovery of Possible Impact Crater at Nevada's
Black Rock Desert". (The word "possible" was added.)
I'm still certain that it's an impact and cannot possibly be a volcanic caldera, based on having been there. (Yes, even though a caldera also would be a significant discovery. Too many things there are inconsistent with volcanoes, exactly in ways that are consistent with impacts.) But since the items I called hard evidence (the Jan 28 shatter cones and apparent shocked quartz) weren't accepted as such based on the photos, I can call it "possible" and wait for others to study it. That still completely accomplishes the goals of posting this information. |
| Feb 16, 2007 | Added the "Related pages on this site" box with an initial link to "Preview: Geological Map of Black Rock based on Satellite Imagery". |
| Feb 21, 2007 | Added link to SciScoop.com page under Where People are Talking About It. |
| Mar 6, 2007 | Added link to Slashdot user journal page under Where People are Talking About It. |
| Mar 8, 2007 | Added link to Slashdot front-page article under Where People are Talking About It. |
| Mar 9, 2007 | Added link to WikiNews article under Where People are Talking About It. |
| Mar 17, 2007 | Added link to BBC News article about Victoria Island impact structure near Stockton CA under "related links" in References. |
| Aug 17, 2007 | Added link to my new "Southern Rings" view of Black Rock Desert suspected impact site page. |
