Stone City Bluffs Mr. Rushing’s 6th grade
So what is geology • And why do we care?
Why do they call it that? • This location is famous for being the most fossiliferous site in Texas! (so far) • But that’s not why they call it Whiskey Bridge….. • They have called it this because this was the closest place that Aggies could get a drink during prohibition. Brazos County was dry but Burleson County was not.
Moseley Ferry? • Stone City Bluffs, alias Whiskey Bridge was also called Moseley Ferry • After the Brazos River crossing in the early days of Texas • Before it was a Bridge, it was a ferry • And before it was a ferry it was a ford. • So this area has a long history
Who first discovered it? A German geologist named Roemer in 1848. He was sent here by the Berlin Academy of Sciences to see if Texas was fit for settlement!
Many people come here to collect and study the geologic formations One of my professors at Texas A&M, Dr. Yancey is one of the foremost experts on this depositional environment.
How old…. • Geologic time is sometimes a little hard to understand…. • We talk about things that are millions and billions of years old. • To make sense of things we name different time periods • Like the dinosaurs disappeared during the Cretaceous-Tertiary Boundary. • But that was before the Whiskey Bridge fossils were deposited.
How old is this ? • Exposed strata (rock layers) in the Whiskey Bridge area are about 35 million years old • To get a better handle on how long ago that was in Earth’s history – we have rocks on Earth that we have dated to be 4.6 BILLION years old • In that respect, 35 million years ago is just a blink of your eyes!
How old is that old? • So, the fossils you found are that old!! • Man has only been around for about 200,000 years and that is a tiny fraction of the age of the rocks that you will see in your samples. • The key geologic material in this area is glauconite.
But what is glauconite… • It is a blue-green sandy material (glaukos is Greek for color). • How did it get here? • The rivers carry sand, silt and clay into the ocean. The glauconite started out as clay and was chemically changed by the ocean and the creatures that lived there.
Fossil Hunting • What are we looking for? • Snails as predators?
More things to look for • Clams • BUT the most sought after (and rarest) fossils are the squid beaks and shark teeth • You could find them in your samples.
Most common • You have a sheet with the 50 most common fossils found in this area. Using your hands and tools, try to identify as many fossils as you can.
But there isn’t any ocean here? • Now there isn’t • But for many hundreds of thousands to millions of years most of Texas was under water! • Actually, somewhere between 50 and 200 feet of water. • What would happen if we had that much water here now?
What was the “hard” stuff • Some of your samples also had some hard material that was tough to break off with your hands • This is a thicker cemented layer of siderite (an iron carbonate) hardground which is resistent to weathering and is the reason that the bluffs remain higher. • Siderite also means that there was low sedimentation rates at the time it was deposited.
What did our class find • So, how could we analyze our results? • What kind of questions could we ask?
(biometrics) or relative numbers • How many predator fossils did you identify? • How many prey fossils? Predator vs. Prey Large vs. Small • How many large fossils did you identify? • How many small fossils did you identify?