Category Archives: Flintknapping

Whirlpool Springs to Life in Onion Creek above Cripple Crawfish Cave

Commander Ben near the Cripple Crawfish Cave whirlpool in Onion Creek

As part of National Ground Water Awareness Week earlier this month, the City of Austin’s Wildland Conservation Division scheduled a “wonderful whirlpool” hike along Onion Creek.

What a fantastic place and what a rare treat to see so much green vegetation and water. We’ve been under a terrible drought in Texas. (The water level on Lake Travis dropped so low that I was able to walk to the sometimes islands late last year. These islands are normally submerged when the Highland Lakes are full.)

We’ve been blessed with recent rains. The rainwater has given life back to our land, lakes, and creeks. I hope that we keep getting more rain.

Karst features help recharge the Edwards Aquifer

The Orr Track on Onion Creek is part of the Barton Springs recharge segment of the Edwards Aquifer. Water that falls on the savannah and prairie land in this area flows through karst features to reach the aquifer underneath.

Carbon Dioxide (CO2) in the air and water (H20) combine to create carbonic acid H2CO3. This acid eats the calcite in the limestone under the soil to create the karst features, and these features consists of big and small cracks and caves under the surface.

Slowly draining karst feature near Onion Creek

Because of our recent rains, there’s water on the surface, but it’s slowly draining underground with the small cracks in this karst.

Dry karst feature with flint rocks

This karst feature has bigger cracks, which causes it to drain faster. There’s no standing water here, but there’s lots of flint. Dr. Kevin Thuesen, Environmental Conservation Program Manager, helped to lead our hike, and he said that there’s evidence of native Americas in this area who have tried out the different pieces of flint to see if any would be good to use.

(I had a chance to try out flintknapping and other great nature activities at the Wild Basin Preserve a few months ago.)

Karst feature with a huge draining crack

This karst feature has a huge crack to help water drain quickly to the aquifer. No standing water here.

Watch out for the rattlesnakes

We saw a few rattlesnakes on our hike, and Dr. Thuesen cautioned us to watch out for them. When the snake started rattling as I walked by, my heart jumped!

This one was near the karst feature with the huge crack, and it was very hard to see at first. (Can you spot the rattlesnake in this picture?)

No snake in this picture, but here’s evidence of feral hogs. They were digging for food (grubs?) in this area earlier. They’re omnivores and will eat just about anything.

Wonderful whirlpool!

Cripple Crawfish Cave Whirlpool in Onion Creek

The treat at the far end of the hike was the whirlpool that flows into Cripple Crawfish Cave (another karst feature!) in Onion Creek. They haven’t seen water in the creek for about a year, so this was a special occasion.

Dr. Thuesen said that they installed a screen over the cave opening to keep out debris and to help water flow more easily into the cave and eventually into the aquifer. Scientists have used a special dye to discover that water that flows down this whirlpool can reach Barton Springs Pool in about 22 days or so.

I’ve only seen a whirlpool in my bathtub before. It was great to see a real one in nature!

Thanks for the great hike!

Ms. Amanda Ross, Commander Ben, and Dr. Kevin Thuesen and the end of our wonderful whirlpool hike

Thank you Ms. Amanda Ross, Conservation Program Coordinator, Dr. Thuesen, and the other knowledgeable guides for the fantastic hike!

Ms. Ross has always been kind and helpful, and she had some neat posters. (I first met Ms. Ross when I learned about rare Texas plants and took a tour of the Balcones Canyonlands Preserve.)

I enjoyed talking with Dr. Thuesen about the different rattlesnakes. He also knew a lot about invasive plants and talked with me about some of the ones in the area, including the Malta star-thistle and King Ranch Bluestem (KR Bluestem).

Don’t miss these wonderful hikes to learn about the native ecosystems of Central Texas. Check out the latest events on the City of Austin’s Wildland Conservation Division event page and be sure to join their email list to learn about upcoming events.

Commander Ben signing off


Filed under Austin Water Utility's Wildland Conservation Division, Balcones Canyonlands Preserve, City of Austin, City of Austin Wildland Conservation Division, City of Austin’s Wildland Conservation Division, Cripple Crawfish Cave, Dr. Kevin Thuesen, Edwards Aquifer, Flintknapping, Karst features, King Ranch Bluestem, KR Bluestem, Lake Travis, Malta star-thistle, Ms. Amanda Ross, Onion Creek, Rattlesnakes, Texas Drought, Texas Invasives, Whirlpool

Flintknapping and Great Nature Activities at the Wild Basin Wilderness Preserve

Commander Ben joins flintknapping craftsman JC Pollard and Kim Johnson at the Wild Basin Wilderness Preserve

Earlier this month, I had a great time at the Wild Basin Wilderness Preserve, learning all about flintknapping from JC Pollard, a talented craftsman.

He taught our group how to create an arrowhead from flint and talked about how heat treating a piece of flint in a kiln makes it easier to flake pieces of the flint off and shape your arrowhead. He also warned us not to put a piece of flint directly in a fire since it would just pop and break apart.

I created two arrowheads from larger pieces of flint. Mr. Pollard let us borrow his tools, and Kim Johnson, who is the volunteer and administrative coordinator at the preserve, also let us use safety glasses for the activity. Mr. Pollard said that copper is much better to use than other flintknapping tools since it is similar in density to a deer antler, which is what the native Indian tribes would have used.

Thanks, Mr. Pollard, for the wonderful experience! With my spearpoint, now I’m armed and ready for those invasives!

A nature jewel in the Texas Hill Country under siege by invasive species

The preserve helps to keep a wonderful part of Austin undeveloped and available for habitat and enjoyment. It’s part of the Balcones Canyonlands Preserve (BCP), but it too is under siege by invasive species.

Mr. Mitch Robinson talked with me about how the preserve was being invaded by ornamentals that are not native to Texas. The invasive plants are moving in from properties surrounding the preserve, and these invasives crowd out native species, create dense monocultures, and present a fire hazard.

Fortunately, he’s helping to teach neighbors to the preserve about the harm that invasive species bring to our ecosystem and to encourage them to plant native species. A dedicated team of volunteers also come out during land management workdays each month to help remove invasive species. That’s great!

During the 2011 Texas invasives conference, I had an opportunity to talk with Mr. Robinson and found out which easy-to-grow ornamental is his least favorite invasive plant.

Many great activities at the preserve

I remember one of my first visits to the Wild Basin Wilderness Preserve many years ago. My Dad and Mom drove down a dirt road from loop 360 in Austin to the main house at the preserve, and I spent the afternoon with a crowd of kids learning about insects. The entire open area was filled with different insect exhibits.

I think I remember touching a hissing cockroach. (There were a lot of bugs to look at or handle there!) I remember a bee keeper talking about the loss of bees because of a mite or some environmental problems which lead to the collapse of many bee colonies.

I’d encourage you to visit the Wild Basin Wilderness Preserve and be a part of one of the many upcoming activities. I loved flintknapping, and in the future, I’m looking forward to stargazing on the preserve (which is hosted by the Austin Astronomical Society), removing invasives, and learning more about the wonder and beauty of our environment.

Commander Ben signing off…

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Filed under 2011 Texas Invasive Plant Conference, Austin Astronomical Society, Balcones Canyonlands Preserve, Flintknapping, Mitch Robinson, Ms. Kim Johnson, Wild Basin Wilderness Preserve