Austin Chalk Hunt 2/4/12 ***several Finds***

[surfergirlatx]

I brought up a question on another of your posts regarding the matrix at this locality. Austin Chalk...Per Wiki: The Austin Chalk consists of recrystalized, fossiliferous, interbedded chalks and marls.

Being familiar with marls...this indicated to me the matrix would be soft...If soaked in water over night it would become soft...at least the outer layer. However, a member replied that the Austin Chalk around Dallas is harder than nails

I know your not interested in preparation beyond tooth brush and water and that's OK...However, I was just wondering about the Austin Chalk at this locality. Does it seem to be noticeably softer when wet?

Yes Indy, without a doubt....when its wet...its mud...not clay like from the Glen Rose when wet....its not sticky when wet, rather just mud that will disintegrate way way way to easy!

[surfergirlatx]

Hi surfergirlatx...

Here is what I can tell you... and I do live in the Cretaceous, both on land and in the mid-continental sea. The thing in photo 21, and any other pieces with similar cross-section.... parallel lines running perpendicular to the length of the fossil are likley pieces of Inoceramid clams. A large common clam from the Late Cretaceous. I htink the nautiloid is an amonite.. it looks too skinny in the end-on view to be a naut. But then I live in the Wyoming part of the sea, not the TX part.

Thank you JPC for helping me to understand the thickness of the cross sections of the Inoceramid clam. Its mind blowing to see how many of these Inoceramid there are here at this location. They seem to be in each and every rock I touch! Happy to know what the thick shell represents! Also thank you for your assistance with the nautiloid being a very weathered ammonite.

Hope to find better quality specimens very soon! Being that its a new hunting site for me, I am still learning what I am finding here. I am used to the Glen Rose Formation and this Austin Chalk is soooo very different.

All my thanks for your time and help!

Kim

Edited February 7, 2012 by surfergirlatx

[jpc]

Kim-

(That's so much easier than all the surfergirl stuff). Yeah, there's places up here too where Inoceramid pieces are a dime a dozen.

jpc

[Indy]

Yes Indy, without a doubt....when its wet...its mud...not clay like from the Glen Rose when wet....

its not sticky when wet, rather just mud that will disintegrate way way way to easy!

Well...I'm sure that makes all those who hunt the "hard" Austin Chalk

around Dallas...Jealous

My Link

Edited February 7, 2012 by Indy

[vertman]

The last find looks like a nautiloid. (I can't make out any sutures, but Im pretty sure its still a nautiloid).

And believe it or not, the individual that found the swordfish skull and the teleost fish was the 12 year old son of a good friend.

And for you DFW folks. It was smack dab right in the middle of a West Plano housing complex. Personally, up to that point, I would have NEVER thought to look there. The Telost fish is pictured in one of Mark McKenzie's books for the Dallas Paleo Society.

Not to sound negative, but in an attempt to bring balance to the DFW force...

It is true you can find absolutely spectaclar finds in the Austin Chalk around DFW and elsewhere. However...the time investement vs. significant finds ratio is way out of whack when compared to other more "fossiliferous" exposures around here. You can look for a hundred hours and not find anything. Then, bam, a beautiful vertebrate fossil exquisitely preserved jumps to light. I have seen fish, shark tooth tentitions, mosasaur remains, giant oysters, ammonites of up to 48 inches diameter, and many other great things.

I don't want anyone to be discouraged by my posting here. It is definitely worth the time investment to look in all the Austin you can. But be aware you will go home almost completely empty-handed more times than not and those spectacular finds are elusive.

[surfergirlatx]

Not to sound negative, but in an attempt to bring balance to the DFW force...

It is true you can find absolutely spectaclar finds in the Austin Chalk around DFW and elsewhere. However...the time investement vs. significant finds ratio is way out of whack when compared to other more "fossiliferous" exposures around here. You can look for a hundred hours and not find anything. Then, bam, a beautiful vertebrate fossil exquisitely preserved jumps to light. I have seen fish, shark tooth tentitions, mosasaur remains, giant oysters, ammonites of up to 48 inches diameter, and many other great things.

I don't want anyone to be discouraged by my posting here. It is definitely worth the time investment to look in all the Austin you can. But be aware you will go home almost completely empty-handed more times than not and those spectacular finds are elusive.

Hi vertman! I dont find your post negative nor discouraging at all. For some strange reason...everytime I go hunting, I bring home literally hundreds of pounds of fossils. I have some kind of fossil powers or something. I cant explain it. This hunt on this thread I posted in only about half of what I found and I did all this hunting in about 1 1/2 hours - alone. From what I hear, most fossil hunters do not find nearly the fossils I for some reason find.

I dont know if its a gift or a curse....my house, sheds, storage, garage, horse barn, every corner I can find is over flowing with fossils....and they are so heavy and I have a bad back, but I cant stop. I am just happy to share my finds with others, for those that are not as lucky to bring home hundreds of pounds of fossils...way more often than I should. Maybe I need to see a doctor???

Edited February 7, 2012 by surfergirlatx

[Missourian]

Not to sound negative, but in an attempt to bring balance to the DFW force...

It is true you can find absolutely spectaclar finds in the Austin Chalk around DFW and elsewhere. However...the time investement vs. significant finds ratio is way out of whack when compared to other more "fossiliferous" exposures around here. You can look for a hundred hours and not find anything. Then, bam, a beautiful vertebrate fossil exquisitely preserved jumps to light. I have seen fish, shark tooth tentitions, mosasaur remains, giant oysters, ammonites of up to 48 inches diameter, and many other great things.

I don't want anyone to be discouraged by my posting here. It is definitely worth the time investment to look in all the Austin you can. But be aware you will go home almost completely empty-handed more times than not and those spectacular finds are elusive.

I thought this was true with fossil collecting in general.

[Indy]

The HUGE clam (pics 4 and 5)

The "Fragment" is 2 feet long...WOW

Well, since I didn't see any comments about this monster...I guess its a wow thing for me,

but not for those who hunt the Cretaceous of Texas

Wondering if these Huge clams are a common find in the Cretaceous of Texas

if so that verifies the rumor...Everything is bigger in Texas

Photo 25

I've seen the shell? pattern before posted on our forum?

Can't remember where

Photos 30-31

I see what would remind you of plant.

Enlarged and edited

Possibly someone will recognize what this represents?

Photo 33

Appears to me to be shell fragment.

Photos 41-44

Nautiloid or Ammonite

Edited February 7, 2012 by Indy

[Boneman007]

The clams are very common.

And you could soak the Austin Chalk from Dallas in water for a week and it wouldn't turn to mud. It's so hard it costs an extra $10K to build a pool if you are sitting on the chalk.\

If I found a good fossil in it, I would end up renting a diamond plunge saw to get it out...

Edited February 7, 2012 by Boneman007

[surfergirlatx]

The HUGE clam (pics 4 and 5)

The "Fragment" is 2 feet long...WOW

Well, since I didn't see any comments about this monster...I guess its a wow thing for me,

but not for those who hunt the Cretaceous of Texas

Wondering if these Huge clams are a common find in the Cretaceous of Texas

if so that verifies the rumor...Everything is bigger in Texas

Photo 25

I've seen the shell? pattern before posted on our forum?

Can't remember where

Photos 30-31

I see what would remind you of plant.

Enlarged and edited

Possibly someone will recognize what this represents?

Photo 33

Appears to me to be shell fragment.

Photos 41-44

Nautiloid or Ammonite

That huge clam is a first for me? Not sure how common they are here in Texas. I am doing a bit of research on it still

Too bad your primary focus is Carboniferous!!!

Well...good thing for books and the internet for me!

[surfergirlatx]

The clams are very common.

And you could soak the Austin Chalk from Dallas in water for a week and it wouldn't turn to mud. It's so hard it costs an extra $10K to build a pool if you are sitting on the chalk.\

If I found a good fossil in it, I would end up renting a diamond plunge saw to get it out...

Very interesting Boneman007.....Starting to think maybe I am NOT in the Austin Chalk formation......I know the property in North Central Texas where I have been hunting is on a fault zone and being that so many roads have been built in this area...trying to keep that in mind. From the "Austin Sheet" - I have narrowed down what formations I feel best match this new area I am hunting. Its NOT hard rock...that is a FACT! It crumbles almost just by looking at it

[Indy]

Its NOT hard rock...that is a FACT! It crumbles almost just by looking at it

What you are describing is Marl and if I remember correctly...The same

Marl that you find in zones at the lake...???

Per Wiki: The Austin Chalk consists of recrystalized, fossiliferous,

interbedded chalks and marls.

Edited February 7, 2012 by Indy

[erose]

Kim,

You are definitely in the Austin Chalk Group. Down here in Central Texas the Austin is very thick and made up of many formations. Some of them are very rich in fossils and some are not. Since we are not seeing Exogyra or Pycnodonte aucella I am guessing you are in one of the lower formations such as the Atco or Vinson. But the Vinson is usually chalkier so that might be what you are collecting in. But that is a complete SWAG on my part.

The one fossil that shows up throughout the group is Inoceramus, and it's relatives. There are many subgenera and species present so naming them to species level can be tricky without excellent, complete specimens. You have probably 3-4 types from this location. Some have more wrinkles, some are flatter, some are bigger. Almost all of your shell fragments are Inoceramus, both smooth and wrinkled. I agree that last one is a nice ammonite. Most excellent. Your IDs seem pretty good on the other stuff as well. Maybe some of the longer rusty things might be burrows, trace fossils.

As folks have pointed out the Austin between here and Dallas changes in many ways. Fossils up that way tend to be less abundant but can also be spectacular. Down here in the Austin area it depends on the formation. The Dessau is packed with stuff while the Atco can appear barren.

As I have studied geology over the years I have come to understand the importance of knowing what weathering does and how some very similar rocks weather differently. The bright white Austin Chalk is known for weathering into a dark rich soil. This is all part of what makes up the very fertile Black land Prairie of Texas.

Considering what you have found so far I would guess you will be showing us plenty more as you continue to collect this site.

Take care,

Erich

[Indy]

Kim,

You are definitely in the Austin Chalk Group......

Erich

Excellent Summary

[surfergirlatx]

Kim,

You are definitely in the Austin Chalk Group. Down here in Central Texas the Austin is very thick and made up of many formations. Some of them are very rich in fossils and some are not. Since we are not seeing Exogyra or Pycnodonte aucella I am guessing you are in one of the lower formations such as the Atco or Vinson. But the Vinson is usually chalkier so that might be what you are collecting in. But that is a complete SWAG on my part.

The one fossil that shows up throughout the group is Inoceramus, and it's relatives. There are many subgenera and species present so naming them to species level can be tricky without excellent, complete specimens. You have probably 3-4 types from this location. Some have more wrinkles, some are flatter, some are bigger. Almost all of your shell fragments are Inoceramus, both smooth and wrinkled. I agree that last one is a nice ammonite. Most excellent. Your IDs seem pretty good on the other stuff as well. Maybe some of the longer rusty things might be burrows, trace fossils.

As folks have pointed out the Austin between here and Dallas changes in many ways. Fossils up that way tend to be less abundant but can also be spectacular. Down here in the Austin area it depends on the formation. The Dessau is packed with stuff while the Atco can appear barren.

As I have studied geology over the years I have come to understand the importance of knowing what weathering does and how some very similar rocks weather differently. The bright white Austin Chalk is known for weathering into a dark rich soil. This is all part of what makes up the very fertile Black land Prairie of Texas.

Considering what you have found so far I would guess you will be showing us plenty more as you continue to collect this site.

Take care,

Erich

Erich...THANK YOU! I can now relax a bit! Trying to research a formation for a new site has proven to be most challenging....so rather that do all that research...I will just hunt for fossils, fossils and yes, more fossils!

Thank you for explaining that the Austin Chalk from here to Dallas can differ. Makes since.

Edited February 7, 2012 by surfergirlatx

[surfergirlatx]

Excellent Summary

Agreed!!!!!

[Boneman007]

Austin Chalk - Dallas County

The Austin Chalk is considered by many to be a group of formations. The Austin Chalk has five members. From bottom to top is the Atco Member, the Austin Chalk, Blossom Sand, Brownstown Marl and Gober Chalk. In Dallas County, the Geologic Atlas of Texas, Dallas Sheet has not differentiated mapped area. Specifically, the condensed section at the base of the Atco Member and known as the Fish Bed Conglomerate is present where the Austin Chalk-Eagle Ford Group contact outcrops. The Fish Bed Conglomerate is a light greenish sandy calcareous clay. Phosphate nodules are abundant. However, the reason for the name is the extreme abundance of small to microscopic fish teeth. The easiest way to collect from the Fish Bed Conglomerate is to submerse large chunks of material in a weak acid bath like vinegar for a few days then wash the material through a fine sieve to catch the teeth. The acid bath and wash may have to be repeated several time. the There used to be a great exposure along FM 1382 west of Clark Road in Cedar Hill, Texas. Unfortunately, a retaining was was erected prevent erosion and rock falls along the sharp and tall roadcut.

I guess what I am talking about is the Atco member of the Austin Chalk

Edited February 7, 2012 by Boneman007

[vertman]

I thought this was true with fossil collecting in general.

Yep, but around Dallas/Ft. Worth it is especially true of the Austin Chalk. Just about any other geological formation exposed here is vastly more productive fossil-wise.

[surfergirlatx]

The Austin Chalk I am hunting is in Williamson County, near Georgetown, Texas.

[Taxman56]

Wow , now I wish I had time to split some of that giant pile I found along a highway last summer on an gas/oil well instalation.

Nothing was popping out, so I didn't spend to much time there. But I found a lot of those giant clams in some giant piles of waste rock at a construction yard in DFW area.

[feeshy1]

My 5 yr old son and i find TONS of the giant Inoceramas ...some of them a fooot or more wide and 1/2 inch thick but they break with any contact in the creek just a half mile from my house if that just downstream from where dps excavated the mosasuar skull fromm that hard a$$ rock in garland a couple years ago ...i wish it wasnt so hard to get to cuz I know the rest of it is right there ...ya gotta have power tools to break through that stuff....we also find a few small exogyra and well thats about it but we keep hoping that someday we'll find that once in a lifetime fossil!

[surfergirlatx]

My 5 yr old son and i find TONS of the giant Inoceramas ...some of them a fooot or more wide and 1/2 inch thick but they break with any contact in the creek just a half mile from my house if that just downstream from where dps excavated the mosasuar skull fromm that hard a$$ rock in garland a couple years ago ...i wish it wasnt so hard to get to cuz I know the rest of it is right there ...ya gotta have power tools to break through that stuff....we also find a few small exogyra and well thats about it but we keep hoping that someday we'll find that once in a lifetime fossil!

"we keep hoping that someday we'll find that once in a lifetime fossil! "

......

Couldnt have said it better myself!!!

Happy Hunting!

[squalicorax]

Congrats on the nice stuff Surfergirlatx, lucky for you Tejas has more fossils than people and the diversity you have seen will never cease to amaze.