Snooping Around the Loop 360 Cuts

[Mikrogeophagus]

A week ago I made the trip out to one of the roadcuts on loop 360. I realized that I had been neglecting visiting the west side of town which, although very different, is just as rich in fossil history as the younger east. I want to also thank @erose as he has posted lots of useful information on the cuts and what sorts of things can be found. 

 

I arrived in the afternoon and slowly climbed up the gravel to get to the first bench. I made the rare good decision to hunt on the side of the road that would shield me from the sun, making the temperature nice and cool, perfect for fossiling. Despite the proximity of the road, the area felt surprisingly secluded. All atop the bench were a variety of giant boulders that had fallen from the many formations overhead. I wasn't sure which ones were best to look through, so I ended up going mostly for the softest ones. They were absolutely packed with everything from gastropods and bivalves to the occasional tiny regular echinoid or algal fruiting body.

 

 

I took occasional trips up the gravelly incline to the top of the cut, but really it was just more of the same stuff so I decided to focus on the easier-to-traverse ground below. It really didn't take long before my pockets were heavy. The day was periodically graced with more unusual finds like irregular echies and a large fragment of an ammonite (whole ones are very rare here). Before I knew it, the sun was beginning to set and it was time to head back to the car. Most of the stuff was pretty easy to clean at home. A lot of the limestone popped right off, though some was a bit harder to get. An interesting thing I noticed was that some of the fossils had distinct parallel engravings on them. It looked a bit similar to the damage I have caused using vinegar on limestone fossils in the past. I wonder if acid rain was the cause for these markings. Anyways, here are some pictures.

 

Overview of the better finds:

 

A). Irregular Echinoids Heteraster texanus

 

B). Regular Echinoids. All Loriolia?

 

C). Misc: Metengonoceras? ammonite on top. Below from left to right is a Porocystis globularis algal fruiting body, Neithea texana scallop, and Ceratostreon texanum oyster

 

D). Gastropods. Back row: Anchura. Front row (L to R): Nerinea? (From Bull Creek Fm), Unknown, and Natica

 

I will definitely be back in the future and might check out some of the other cuts nearby. Thanks for reading!

[GPayton]

I love that spot! I've only been once but one of my prized possessions is the first Loriolia I found amongst the big boulders. They get surprisingly small. I'm fairly certain I have one that's only about a quarter of the size of my fingernail.

I also didn't know that Porocystis could be found there - they're really hard to spot, so congrats on the find! 

Edited September 6, 2022 by GPayton

[erose]

Cooly Cool! The large regular echinoid fragment is probably a Phymosoma. The small ones are most definitely Loriolia.  The Neithea is N. irregularis not N. texana.

Every thing else appears spot on.

 

There are three formations present at that cut.  You were collecting in the Walnut Formation.  There are three members there. The first bench itself is the massively hard Bull Creek Member, Above that is the Bee Cave Member which is mostly buried under talus made up of the Cedar Park Member as it falls down.  The very top-most cliff is the bottom of the Edwards Formation and the yellow-tan layers down below along the road are the top-most layers of the Glen Rose Formation. Oh, and there is NO Comanche Peak at this location.

 

I have collected some really good stuff from there. Including a few(?) other echinoid species, some odd moluscs, small corals and a few good crustacean bits.

[Mikrogeophagus]

Small Update:

 

I made a quick trip to the cut on the other side of the road today between classes and a dinner to see if it was more accessible or had any differences in terms of what could be found. I found it to be a bit easier to climb on, but similar fossil-wise as expected. I'm happy I took this short stop because I managed to find a decently-sized regular urchin that I feel is worth sharing. From what I can see online, I'm guessing this is Phymosoma like the larger fragment I found in my first trip to the spot.

 

[JohnJ]

2 minutes ago, EPIKLULSXDDDDD said:

I'm guessing this is Phymosoma like the larger fragment I found in my first trip to the spot.

Indeed!  A primary characteristic is non-perforate tubercles.

[erose]

Yes indeed! Should clean up well.

[FossilNerd]

Nice report and finds! I’ve always had a soft spot for echinoids. Unfortunately there are none to be found here. Still, I hunt them vicariously through reports like this. Thanks for posting!

[Jared C]

4 hours ago, EPIKLULSXDDDDD said:

I'm happy I took this short stop because I managed to find a decently-sized regular urchin that I feel is worth sharing

I'm curious to see whether you'll pull a hard to come by Tetragramma out of there. With your invertebrate hot streak in the Ozan and this beautiful Phymosoma you might have some momentum going now 

[erose]

4 hours ago, Jared C said:

I'm curious to see whether you'll pull a hard to come by Tetragramma out of there. With your invertebrate hot streak in the Ozan and this beautiful Phymosoma you might have some momentum going now 

I’ve been collecting that cut since 2006 and there has been no sign of Tetragramma in the lower Walnut members. They don’t seem to show up until the younger Keys Valley Member. A little bit of a mystery. Another mystery that JohnJ. Has always pointed out to me is that there is also no sign of any cidarid in the Walnut or Comanche Peak.

[Mikrogeophagus]

22 hours ago, Jared C said:

I'm curious to see whether you'll pull a hard to come by Tetragramma out of there

Now that I think of it, there's chance I'll find a Tetragramma as well as other cool echies at my next stop during my brief visit to San Antonio soon. Hopefully the invert hot streak stays hot.

[erose]

8 hours ago, EPIKLULSXDDDDD said:

Now that I think of it, there's chance I'll find a Tetragramma as well as other cool echies at my next stop during my brief visit to San Antonio soon. Hopefully the invert hot streak stays hot.

Do you know what formations you will be collecting down in San Antonio?  There seem to be a variety of Tetragrammas that show up in the Glen Rose Fm.  But for Tetragrammas in the Walnut you need to head north into the younger members like the Keys Valley member or up into the Comanche Peak Formation.

[Mikrogeophagus]

54 minutes ago, erose said:

Do you know what formations you will be collecting down in San Antonio?  There seem to be a variety of Tetragrammas that show up in the Glen Rose Fm.  But for Tetragrammas in the Walnut you need to head north into the younger members like the Keys Valley member or up into the Comanche Peak Formation.

The spot I’m going to is mostly lower glen rose and is a bit famous. I won’t name it yet, but if I make a new topic after I will. 

[JohnJ]

1 minute ago, EPIKLULSXDDDDD said:

The spot I’m going to is mostly lower glen rose and is a bit famous. I won’t name it yet, but if I make a new topic after I will. 

 

As a general rule and regardless of 'fame', it would be better for continued access to the site if you didn't.  A very broad regional description and geologic formation are all that is needed to provide context.  

[Mikrogeophagus]

17 minutes ago, JohnJ said:

 

As a general rule and regardless of 'fame', it would be better for continued access to the site if you didn't.  A very broad regional description and geologic formation are all that is needed to provide context.  

Fair enough  

[Kane]

Congratulations on your new honey hole! Keep that information close to your chest, but do continue showing us the lovely spoils of your collecting from the site.  

[erose]

9 hours ago, EPIKLULSXDDDDD said:

The spot I’m going to is mostly lower glen rose and is a bit famous. I won’t name it yet, but if I make a new topic after I will. 

Like JohnJ said you don’t need to divulge the site. Lower Glen Rose is enough. There is a small Tetragramma species in the Lower GR as well as larger one(s) that have yet to sorted out. Good luck.

[PaleoPastels]

Loop 360 is in Austin, correct!? Because that sounds super familiar. No matter ya’ll are REALLY making me want to brave the heat and go out.   Ive been wanting to add some heart urchins to my collection as they’ve their cuteness has been really growing on me. I had no idea we were allowed to surface pick on road cuts! Ive passed by some nice promising ones before here the past decade and dreamed of doing so…but assumed we couldn't legally do that.  Something I need to look into I guess!  

[Mikrogeophagus]

Yep I was in Austin for this. Road cuts are pretty great for hunting in limestone formations, just watch out for cars of course. Careful though, you might find a regular echinoid and fall down the rabbit hole...

[PaleoPastels]

8 hours ago, EPIKLULSXDDDDD said:

Yep I was in Austin for this. Road cuts are pretty great for hunting in limestone formations, just watch out for cars of course. Careful though, you might find a regular echinoid and fall down the rabbit hole...

Wouldn’t mind falling in a mental rabbit hole of echs  Seriously I need to come down to Austin sometime! A 3 hour drive for me but seems worth it! 

[Mikrogeophagus]

26 minutes ago, AmmoniteDelight said:

 Seriously I need to come down to Austin sometime! A 3 hour drive for me but seems worth it! 

Well if you do, feel free to reach out to me. I don't have that many spots, but I could share a couple!

[BobC]

Speaking of "surprisingly small" Loriolias--I know a place in Austin where there are tons of them that are just a fraction of an inch. I never even noticed them until I got new glasses! Anyway, nice finds

[Mikrogeophagus]

Instead of making a new post, I thought I'd post an update here. After my classes, I decided to go on a hunt at the cuts given the recent rains. One of my goals heading in was to find a Coenholectypus urchin. I've found a barely recognizable one in the past from the Pawpaw or Weno, but I've really wanted to pick up a nice one that can be displayed. Of course, I'd have been happy with some nice-sized regular urchins of other genus's as well. The site was muddy, as you could probably imagine. I spent the whole time climbing up and sliding down the slopes, so it was a good workout. About halfway through, I came across a specimen that was urchin-shaped and had some subtle bumpy texture to it. I tried to clean it off, but that just smeared the mud even more. I decided to keep hold of it for when I could do some proper cleaning. By the end of the day, I had forgotten about. I didn't find anything spectacular, so I was honestly a bit down. When I got back and rediscovered the possibly urchin, I immediately gave it a nice brushing and was pleasantly surprised to find the beautiful surface of a Coenholectypus urchin! 

 

 

I don't know how much cleaning I want to do with it since it's a bit fragile and I don't want to mess it up. Might have it professionally done one day, we'll see. Either way, I'm pretty happy and I hope you all enjoyed reading this quick update!

[erose]

Not a bad specimen. Sooner or later you'll find a specimen free of the matrix and much simpler to clean up. Those 360 road cuts will produce good specimens.  But we are going to need a LOT more rain.