Advice for Marble Mountain Trilobite hunting in the Mojave

[Ori]

Hello! I am new to fossil hunting and want to plan a weekend trip to the marble mountain trilobite collecting area in the mojave desert. I've read about two collecting methods - sorting through shale discarded by previous visitors, and splitting new layers of shale. Would it be worth it for me to get the tools needed to split shale as a beginner? Or should I stick to sorting through debris? If I want to split shale what should I get? I think I need work gloves, glasses, estwing rock pick, and a chisel + hammer to split the shale (I'm a bit unclear on what type I need). Any advice is greatly appreciated!

 

[FossilDAWG]

You will want to split shale if you want to find complete trilobites.  You may be able to just split chunks left by previous diggers, in which case a bricklayer's hammer with a chisel edge may be quite useful.  I'd bring a few cold chisels as well to get more controlled splits.  Don't forget eye protection!  You may have more luck digging out fresh/larger chunks from the outcrop, but then you will need digging tools (pick and shovel) as well.  My understanding is that you have to remove overburden or talus from previous excavations to get at the fresh rock, although this is only based on what I have heard or read.  @Brett Breakin' Rocks has collected there so maybe he can comment.

 

Don

[Sjfriend]

It is way easier to pick through the talus left by previous hunters. It takes some work and time to get to the fresh layers. Lots of over burden to move (that is all the loose rock piled up on top of the layers). I use a Estwing hammer and a couple chisels to split shale. Any hammer and smaller cold chisels are adequate. The shale is not hard / tough. You can find tons of complete cephalons. Complete specimens are very uncommon. I've probably dug for over 150 hours and found 4 complete trilobites.

 

I'm actually hoping to go there this week for a day or 2.

[minnbuckeye]

10 hours ago, Sjfriend said:

dug for over 150 hours and found 4 complete trilobites.

WOW. That is .25 trilobites if one puts in an 8 hour day! Not great odds.

[jpc]

ah.... but the thrill of finding a complete one is magnified.  

[Brett Breakin' Rocks]

@FossilDAWG Hey Don, indeed. The best bet for complete trilobites is to remove the overburden and start a fresh book/section of shale. Otherwise, if you are ok with pieces of trilos or shed cephalons ? Then you will have plenty of luck just looking in the cast-off shale. 

I will say from lots of experience that finding absolute pristine shale (in my opinion) is not preferred in this location. The -really- cleaner shale is extremely hard and brittle. The bedding planes where the shale will spilt properly, in this pristine shale, are few and far between. I feel like it's akin to what I've heard hunting for Eurypterids is like. The elements need time to work a bit on the rock face. It is also best, if you are on the splitting shale (looking for fossils) to use a sharpened 'wide' chisel.  It makes the chaces of you getting a nice clean sheet much better in this environment. I used heavy duty chisels to clean a space and move overburden. 

I usually tried to find shale bedding that had been somewhat intruded upon by water/fine silt. Letting the environment split the shale to soften it up, and making the bedding planes easier to access. Bring a nice broad brush to wisk away the dirt and mud.

Another tip is to find shale with cephalons (essentially the head), or bits of trilobites and work your way up the hill to find the source. That same 'color' of shale usually has similar trilo examples, and you won't spend your first two hours in a dry hole. There are many. The same goes for the small brachiopods etc. Once I found one, I could usually count on finding several additional exapmples in the same shale horizon.  

Other than that. Don't expect to find a complete trilobite on your first outing. The work is tedious, and usually wicked hot during the summer months. I have probably one flat of complete trilos, and as many that were too fragile, or in the way of my chisel. The cephalons have wonderful preservation. Keep your eyes peeled, most of the complete trilos that exist are under an inch/and covered in dust or dirt. The environment here was probably a fairly high energy one, so the articulated bits were quickly spread about. 

 

If you plan on splitting shale alot I would also recommend a dust mask ?  Eye protection is required. But not too mant folks talk about working this shale and wearing a mask to protect your lungs. Long term exposure would be no-bueno. @Ori

Good Luck,

Brett 

 

Edited December 1 by Brett Breakin' Rocks

[Sjfriend]

15 hours ago, minnbuckeye said:

WOW. That is .25 trilobites if one puts in an 8 hour day! Not great odds.

Nope! It took 3 days to find my 1st. About 3 more for my next, but found 2 that day! Then another big gap. Probably a couple of thousand cephalons between each complete one.

[Sjfriend]

11 hours ago, jpc said:

ah.... but the thrill of finding a complete one is magnified.  

Oh yes! It's like "wait, I am seeing things or is it real?"

[Sjfriend]

As with what @Brett Breakin' Rocks mentioned, a dust mask is a really good idea, especially when moving all the over burden. It's a messy job.

[Brett Breakin' Rocks]

@Ori A few examples of the bits and pieces that are more common. Unfortunate breaks included. One 'mostly' complete specimen. @Sjfriend is not exaggerating. The work vs reward makes this hunt a test of patience. Lighting from the side for contrast. Inches for scale. 

[Ori]

@Brett Breakin' Rocks @Sjfriend Thank you for the advice! I made a day trip there yesterday and will definitely be going back - I could spend days and days there. No complete specimens but I'm pretty happy with what I found! I'll be posting pics soon

[Sjfriend]

9 hours ago, Ori said:

@Brett Breakin' Rocks @Sjfriend Thank you for the advice! I made a day trip there yesterday and will definitely be going back - I could spend days and days there. No complete specimens but I'm pretty happy with what I found! I'll be posting pics soon

Good to hear. I'm heading there tonight for 2 days of digging. Maybe I'll use your hole as a starting point lol

[Ori]

22 minutes ago, Sjfriend said:

Good to hear. I'm heading there tonight for 2 days of digging. Maybe I'll use your hole as a starting point lol

Oh that’s so fun to think about! Yeah there’s a pretty good area cleared of debris, good luck! I wish you whole specimens and and anomalocaris appendages 

[Sjfriend]

On 12/1/2024 at 10:54 AM, Ori said:

Oh that’s so fun to think about! Yeah there’s a pretty good area cleared of debris, good luck! I wish you whole specimens and and anomalocaris appendages 

Well, 23 hours of breaking rock and I found 1 complete trilobite!!! Funny part, if I had set a deadline of quitting after finding a complete one I would have stopped at hour 1. There is so much of the face buried under a ton of over burden. 

[jpc]

We would love to see some pix of the site and of your one cool find.

[Ori]

On 12/5/2024 at 5:29 PM, Sjfriend said:

Well, 23 hours of breaking rock and I found 1 complete trilobite!!! Funny part, if I had set a deadline of quitting after finding a complete one I would have stopped at hour 1. There is so much of the face buried under a ton of over burden. 

Congrats!!  

[Sjfriend]

On 12/5/2024 at 7:26 PM, jpc said:

We would love to see some pix of the site and of your one cool find.

Gonna post a trip report in a bit. Gotta get settled back at home first. Was gone a month so have some chores to do lol. Always a lot to do to get ready for our Alaska winters.