Rolf Luetcke on Fossils

Hi Tom,

Besides being an “old fossil” , my fossil hunting actually goes back to when I was a kid in Germany. My dads’ family house was near a small town and they had a nice piece of land with the old family house on it. The whole area around the house was crushed rock that was brought in to make an area that didn’t get muddy during rains. In among the pieces of rock there were crinoid fossils. I would sit for hours looking in the gravel for pieces with the rounded fossils in them. I had no idea what they were but I remember looking for them.

Never got into fossils in a big way either but knew a bit about them from my college days.

Didn’t get back to fossils until I moved where we are now. I was taking the dogs on morning walks and when I walked, I rarely slowed down, I have always had a fast pace when I am out and hiking. But, having to pee does make one stop and on one hike I stopped to pee and then always looked around and to my amazement, found a bone in a piece of rock just about a mile West of our house. If I had just found the bone I may not have noticed much but thought it was something a coyote had lost but in this case, the bone was par of the rock of the area, a white caliche like material. That got me looking and before long I saw little bone fragments all over the place.

Home again I researched this and got in touch with the University in Tucson. One of the guys there sent me a paper he had written on the fossil history of the San Pedro River Valley. It seems this area was a study area for major Universities from a few places back in the 1930’s and 40’s. They had found this area rich in mammal fossils from recent times to about 5 million years. I was hooked and started looking more and more. Found a bunch of things and was able to identify quite a few species in what I had come across.

Found all sorts of things of the mammal fossils from the area, including Camel, Mastadon, Rhino, Horse and many more. Fun stuff and I have a nice display in the shop/museum of the finds.

There are a number of much more ancient fossils also in the area and those stones I sent photos of are examples.

Lots of shell fossils in the area limestones too. One spot between Tombstone and Bisbee has wonderful layers and each one a different kind of shell life in it.

Never did get into fossils as I did minerals but it was fun to learn some of the history of the area.

One that was both mineral, fossil and lapidary material is Turitella, a fossil material from the West. I got some nice big pieces of it and did a few into jewelry, quite hard stuff. You may look into getting some for your cutting.

Here is a photo of the Turitella I did a cabachon of, neat stuff.

This is fossil Auricaria cone from Argentina, this piece a friend gave me to cut. This material is somewhat protected now by the Argentine govt. it was mostly smuggled out before.

This one is Stromatolite, a fossil algae, and quite ancient. Got some of this to cut from the Illinois friend.

My knowledge of fossils is not that good but I have had fun with the material I have come across.

I am sure you will come across some also in hunting rock. Petrified wood, or pet wood as we call it, is a good example.

Take care


Modern Day Desert Snails

Desert Snails

I recently got an e-mail which touches on a desert snail shell I recently found at Nopah:

Hello! Your geological adventures are so interesting and informative. Here is a screen shot of my Instagram message. Have you seen anything like this? Are these currently living creatures or extinct or fossils that are not stone… which isn’t exactly possible.

If you could point me in the right direction to someone who knows about these things that would be great. My 7 year old is 100% in love with geology.

Also, what info could you pass along to encourage her passion of rocks? What tools are the most fun we could use to help her investigations and learning?
Any professors or books that would be a great resource?

Thanks, A Reader

My reply:

Hello and I hope you are in good health. You most certainly have a present day snail shell. Where did you find it? Location is everything when finding something. There may be, for example, a snail in CO limited to just one mountain range. With that location, someone can better identify an object, compared to having it presented as something from somewhere in CO. Actually, with an exact location, someone can try to identify a specimen 20 years from now!

Desert snails exist today and leave behind their delicate shells when they die. As you know by their weight and fragility, they aren’t fossilized. Yet. You probably saw my gastropod photo from the Nopah, which I misidentified as a brachiopod (those are shells). I’m attaching it in this e-mail.

Professional ecologist Jim Boone identified what I had as definitely a desert snail, in fact, he once edited an academic paper on a snail that turned out to be new to science.  I have that paper belwo.

Apparently, it is very difficult to tell one desert snail from another, consequently, to be safe, one might call them by their genus name, which I think is Eremarionta. That’s like calling Oaks Quercus. All oaks are quercus, even if we don’t know which one we are looking at.

The one page paper you will read is academic and difficult, never-the-less, it mentions important scientists and papers regarding desert snails which you can use to go further.

Although Jim’s site is focused on Southern Nevada, he provides easy to read pages on rocks and vegetation. With your assistance, I am sure you could help your child puzzle out the pages on rocks and geology.

For local rocks, get hold of your local rock club. They love any new member, especially children. They are sometimes called Pebble Pups. (And they often get free stuff, which always makes me jealous :-))

As to reading, Diamond Dan has all sorts of easy to read and extremely accurate publications on minerals:

He has a number of free, downloadable .pdfs for kids to freely download during this COVID-19 practice. I can spare a few of his books if you want.

I wish you well and congratulations on your find. I hope you and your child continue searching. There is a fossil group on FB but any internet forum can get really nasty; I don’t generally don’t recommend them for beginners because of trolls. Best, Thomas

Snails on Yucca Mountain

Text by Will Pratt and the Internet, editing by Jim Boone

(All rights reserved to the authors)

The snails found in Abandoned Wash on Yucca Mountain are Panamint Desertsnails (Eremarionta greggi Miller, 1981) or an undescribed, new species. (Dr. Pratt is working on this question.) If they are E. greggi, then prior to finding these specimens on Yucca Mountain, this species was only known from two sites in California: Johnson Canyon in the Panamint Mountains (Inyo Co.), and in north-facing rockslides along the Silver Lake-Ft. Irwin Road in the Avawatz Mountains (San Bernardino Co.).

The Avawatz range is due south of the Ibex hills, separated by the valley of the Amargosa River. The distribution patterns of these helminthoglyptid snails date from the late Tertiary, and the Death Valley graben dates from the middle Pleistocene. During those time, the Avawatz were likely part of a continuous chain of montane habitats leading north from Avawatz through the Ibex Hills, Black Ridge, Grapevine Mountains, Bullfrog Hills, and Bare Mountain to Yucca Mountain. The Avawatz, Owlshead, Panamint, and Grapevine Mountains form a second such chain of formerly continuous habitat. Thus, it seems that this species could be found throughout these mountain ranges. Because people have not looked for snails in these mountain ranges, what we don’t know about land snail distribution in this region is enormously greater than what we do know.

The genus Eremarionta includes nine species in the United States; all are restricted to southeast California except for one species that extends into extreme western Arizona. This species extends from Temple Bar, Arizona, south along the eastern edge of the Colorado River into Baja California and west to Indio, CA:

(, 1997).

Eremarionta greggi and the Argus desertsnail, Eremariontoides argus (Edson, 1912) are the northernmost members of this group of snails (Eremarionta ranges eastward into southern AZ, in the Sonoran Desert). E. argus is listed in Pilsby’s Land Snail monograph as Micrarionta (Eremarionta) argus, lumped with E. greggi. Although the anatomy is distinctive, the shells cannot be reliably separated.

These snails are found in sheltered rockslides, generally on north-facing slopes with some runoff. While they live underground among the rocks, their shells can be found on the surface in areas they inhabit. It is likely that if we surveyed likely habitat on Yucca Mountain and surrounding montane areas, we would find more sites with these snails.

Prepared by:
Dr. William L. Pratt, Curator of Invertebrates
Marjorie Barrick Museum of Natural History
University of Nevada, Las Vegas Box 454009, Las Vegas, NV 89154-4009

Miller, W. B. 1981. A new genus and a new species of helminthoglyptid land snails from the Mojave Desert of California. Proc. Biol. Soc. Washington, 94: 437-444.

Editor’s note. If you want to go down the rabbit hole with native slugs and snails, check this out:
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Casts, Molds, and Impressions

Can we have a bit of fun here? I thought my rock and mineral backgrounds were boring so I went retro to 1964. This is from my Instagram account which I know many of you do not follow.

Casts, molds, and impressions are confusing terms. Molds are impressions. Casts are relief. To explain, let’s say you wanted to make a beaver footprint cast down by a creek. With some plaster of Paris, you would fill in the footprint the animal left behind. This is an impression or mold in preferably moist soil. Once dry, you would pop out the hardened compound. You now have a cast. A mold needn’t be a track left by a live creature, it can also form when a body fossil decays or dissolves, leaving an impression.

In this video we have a puma track cast. As Authentic Wild relates, “This cast was made from a captive lion taken in as an orphan by the caretakers at the famous Sonoran Desert Museum in the Sonoran Desert in Arizona. An impressive cat.” The simulated impression of a dinosaur track comes from the museum store at the St. George Dinosaur Discovery Site in St. George, Utah. Artist David Slauf replicated the track of a small Grallator, also known as a Katiebell track. SGDS is the place to see all sorts of real casts and impressions. Even the impressions of dinosaur tail dragging!


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For the Shell of It

Went back to the desert wash near Jean,  Nevada where I had found my first geode. Was looking for more. Didn’t find any but I may have found my second and third brachiopod or fossilized shell.

The first example is pretty convincing but the second is a mite odd. I see by a Google image search that brachiopods are often distorted.

Too many times a publication or a web page presents perfect specimens instead of what is usually found in the field. I’ve posted the images to the Fossil Forum on FB, I’ll see what they say.

Phivos Martin Broedsgaard-Raptis from the FB Fossil Page responded to the second specimen. “We call it a ‘mussel fracture’, it comes as a resulted of a concentrated force and radiates outwards from the point of contact.” I am assuming that something injured this poor mussel and the resulting damage was captured in stone.

Or, perhaps not. There is a geological process called plumose fracture. See the Wikipedia Common photo below. Okay, what do we have? A biological phenomenon or a geological one? I’m leaning to biologic because the rock is round and not a square or chip fragment.


Fig. 3.20f: Plumose structure and rib marks on an opening fracture in PMMA. Laboratory experiment (Rummel, 1987) on hydraulic fracturing induced fracture from pressurized cylindrical hole at left. – David D. Pollard

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Internal Cross Section of A Fossil Sponge?

My fellow rockhounds and I have been having great fun trying to figure out what this photograph depicts. I spotted this fossil on a hike a few days ago in the Red Rock National Conservation Area. That’s just a few miles outside of Las Vegas, Nevada. In an area called Fossil Ridge. If you put this GPS decimal coordinate into a browser search bar you’ll call up a map of the location.

36.1123, -115.4247

Due to the sedimentary nature of the area I am thinking the white material may be chert. But since this is a no collection area I couldn’t take anything away. As a matter of fact, I felt good for not touching it and leaving it undisturbed. Due to the number of sponge fossils in the area, a local professional ecologist suggests it could be the exposed internal structure of a sponge fossil.

Update! The joy of discovery through photography. A photograph can be as memorable as anything you pick out of the ground. Dr. Josh Bonde, a local, renowned paleontologist, says this about this image:

“Not having the specimen under my nose always makes it a bit more difficult to provide a positive ID. That said, it looks to me like a stromatoporid sponge. It looks like just up and to the right of the sponge you have part of a brachiopod as well. That’s my guess.”

Isn’t that wonderful? I can now look up this sponge and learn all about it. And did you see what he saw with this low resolution photograph? A brachiopod or shell like organism at the middle and to the right of the sponge. I totally missed it before.

Thanks to all the people who helped me with hints and with finally connecting me to the good professor. I’ll write more about this kind of exploring and collecting in my book.

Click on the photo for a larger image or click here.