The Austin Chalk

After staying the night at the Cypress Bend Resort on Toledo Bend (Toledo Bend Reservoir &  A fox-cypress-bend-resort ), my husband had to be in Austin the next day by six o'clock for a business meeting, and thus the reason for me going on this trip to help with the driving.  It's a six hour drive which different because we were taking back roads that we would probably never had been on if it wasn't for this trip.  We took LA-6 which turned into Tx-21.  While on Tx-21 we drove through 'Sabine National Forest'.  The main thing this forest is famous for is when the Space Shuttle Columbia exploded a lot of the debris ended up in this place.  Its a massive forest and was pretty to see.  A lot of the spring flowers were just starting to bloom.
   From Tx-21 we got onto Tx-103.  The main thing of interest on Tx-103 is Angelina National forest and the Sam Rayburn reservoir.  Pretty rural stuff with it being just two lane roads, it is also part of the Texas Forest Trail.  Because of all the vegetation there were not a whole lot of outcrops to see.  We took Tx -103 till it merged into Tx-7.   
  We drove through 'the Davy Crockett National Forest'.  While we were doing that we couldn't help but to sing the song from the TV show Davy Crockett and talk about how we used to pretend we were frontiers men when the show was airing.  Those were the days and it was fun to be reminded of them.
  Eventually we found Tx-79 and took that to the City of Round Rock.  In Round Rock we were able to get onto the interstate - Hwy -35.  With a name like Round Rock I was interested in seeing the Rock that gave it its name, but our travelings didn't take us near anything that looked like a Round Rock.  I was very disappointed in that.

I could hardly wait to see Austin Texas.  This was only the second time I had ever been there.  The first time was just in passing through and I really didn't get to see much other than the capital building.
   When I was working in the oil patch 30+ years ago the Austin Chalk was a big oil play that was going on at the time. There was a lot of oil in it but it was difficult to recover because it was so tight in places.  The areas that were highly faulted proved to be good reservoirs and some fracking was being tested in it.  While I never had a field in the Austin Chalk, I was hearing so much about it I was just naturally curious about it and read what I could on it. From that point on I always wanted to see it at its source in Austin Texas.   
     Unfortunately most of what I studied has not really stayed with me.  All that I remembered was that in Austin that was where the Chalk outcrops and is the type formation for it. I also remembered it is Upper Cretaceous in age, and it is mostly a limestone and marl.  Since its been so long and I don't trust my memory more than that, I'm including how the USGS describes it Austin Chalk  and here's what Wikipedia has to say about it; Austin Chalk . 
So now here's some pictures I took of it.

Austin Chalk, Austin Tx

This was the first outcrop that I saw where I could tell it was the Austin Chalk.  Everything else I was seeing was mostly sandstone.  While this was white and  just looked like Chalk to me. 
  We ended up staying at the Barton Club resort.  Most of the people that go there go for the golfing and it did have a beautiful view.

Barton Club, Austin Texas

I'm not into golfing but I was interested in its nature trail. It was so neat to actually be able to walk on the Austin Chalk and to get some pictures of it.  And of course I just had to grab a couple of samples too.  I couldn't wait until I got home to see if they would fizz with HCL which it did.
  One of the things that made the walk so nice was coming across this little creek that seemed to be spring fed.

Barton Club nature trail

In reading the 'Roadside Geology of Texas' by Darwin Spearing (1991) on pg 64 he writes 'Springs emanate from limestone aquifers all up and down the length of the Balcones escarpment.  One good example in Austin is found at Barton Springs, a favorite swimming and picnicking site south of the Colorado River.  The water comes to the surface at Barton Springs where a fault has offset a porous unit within the Edwards limestone, which is honeycombed with caves and solution cavities.'
   Since I was at the Barton Club resort I figured this must be one of the springs he was talking about.  But because I was higher up (as seen by the golf greens sloping down toward it) than Barton Creek, I felt  I was in the Austin Chalk and not the Edwards formation although I maybe wrong about that.

A creek flowing through the Austin chalk

 Here's some more images of that nice little creek that was flowing through it.

I followed the creek until it took me to this neat little secluded Grotto. 

Barton Club Grotto, Austin Tx

 And here's a closer look at the Grotto.  (A grotto is a hole eroded in a wall of a cave by seepage or lateral stream erosion. a small cave. Dictionary of Geological Terms)

Barton Club Grotto, Austin Tx

Limestone ledge.

 Here's the resistant ledge that caps the grotto and forms the small water fall.

After I saw the grotto I continued to walk and explore.

Austin Chalk outcrop

I thought this was a pretty interesting showing some vugs in a sandy/ limestone.

Austin Chalk Formation showing a marl layer in it.

 I came across this section and figured this must be a section of marl that they were referring to.

 Most of the stuff I was seeing was like this here below.

Austin Chalk outcrop

Austin Chalk outcrop.

The one thing that struck me was how thin the soil was and how much of the rock I was actually able to see. Also how sparse the vegetation was unlike the lush vegetation we had driven through to get here.  I was not surprise to see cactus growing in the area because I know in that part of Texas its pretty dry most of the time.

Cactus growing on the Austin Chalk

After spending the day there it was time for us to head back home.  We basically followed Hwy 79 all the way back home.  

 I muse:  what I saw was a whole lot more vuggy than I expected.  No wonder it was able to hold so much oil.