Dinosaur Valley State Park: Ballroom Track Site
The largest dinosaur track site in the park gets its name from the many directions of the tracks, as if the dinosaurs were dancing. This site contains nine very large sauropod tracks with mud swells rising 8 inches above the surface. Ten smaller well-preserved juvenile sauropod tracks show evidence that a young sauropod was being pursued by a theropod. That said, the most abundant tracks at this site are from theropods. Some of the tracks form the patterns of trails, but most do not. This track site is often covered in sand and mud. Sometimes only the mud swells surrounding the large sauropod tracks show. The best time of year to see this track area is in the late summer when water levels are lowest.
Geological Attributes of the Glen Rose Formation All of the dinosaur tracks in this area are related to the Glen Rose Formation, which is a shallow marine to shoreline geological formation from the lower Cretaceous period exposed over a large area from South Central to North Central Texas. The formation was named in 1891 for the town of Glen Rose, Texas, by paleontologist Robert T. Hill, where the Glen Rose Formation is exposed in the Paluxy River and numerous dinosaur footprints and trackways have been found. Eastward-dipping limestones, sandstones, and mudstones of the Glen Rose Formation were deposited during the early Cretaceous Period approximately 113 million years ago along the shorelines of an ancient sea, and form the geological setting for the park area. Over the last million years or so, these layered formations have been eroded, dissected and sculpted by the Paluxy River which, in many places, has cut down to resistant beds and planed off sizable exposures of rock in the river bottom.
The Glen Rose Formation outcrops in this area (viewable at the surface), where it composed primarily of limestones (sedimentary rock composed of calcite which is responsible for its chalky texture) as opposed to sandstone (sedimentary rock made of sand like pieces of rocks and minerals like feldspar and quartz).
What kind of dinosaurs left tracks in this area?
SAUROPOD TRACKS: large elephant-like tracks believed to have been made by Sauroposeidon proteles, who were plant eaters and walked on four legs.
THEROPOD TRACKS: smaller and often with a distinct three-toed pattern, believed to have been made by Acrocanthosaurus, a meat eater. Some of the theropod tracks are classified as "elongated" because the dinosaur was walking on its metatarsal bones.
How are dinosaur tracks formed?
Millions of years ago, dinosaurs left their tracks in sediment. Typically, the soil was wet -- part of a shoreline, a mudflat or even the bottom of a shallow sea. As the area dried, the tracks hardened. Eventually, another layer of sediment filled the prints, protecting them from erosion or damage. Very heavy dinosaurs could also leave underprints, stepping so forcefully that they compressed deeper layers of soil, essentially leaving their tracks protected underground. Over millions of years, these layers of sediment hardened into sedimentary rock -- the same type of rock that preserves dinosaurs' fossilized bones. Then, over another long time span, erosion, weathering and geological forces gradually revealed the buried tracks.Fossils in the Glen Rose Formation
A variety of fossils are found in the Glen Rose formation including including numerous gastropods, clams and echinoids. Dinosaur tracks have been found in many localities, as well as isolated vertebrate remains. Typical fossils found in the Glen Rose formation include: Heteraster obliquatus (Clark), an irregular sea urchin.
Salenia texana Credner, a regular sea urchin.
Tylostoma sp., a gastropod.
Arctica gibbosa (Giebel), a "heart clam" (bivalve)
Porocystis globularis (Giebel), an algal fruiting body.
Mostly from fossil findings, Glen Rose strata are known to have been deposited in a "transitional marine" environment, the zone between open ocean and shore. Consequently, digging through the Glen Rose you pass through material ranging from that deposited in deep ocean water, to beach sand in which dinosaur footprints might be found.
In order to get a smiley for this Earthcache, answer the following questions:
1. (Optional) Post a picture of you and/or your party at the listed coordinates with dinosaur tracks.
2. Why is this site referred to as the "Ballroom"?
3. Measure the length of one of the dinosaur tracks. Based on the formula that the height of the dinosaur would be 10x the length of its footprint, how tall was the dinosaur that made the track?
4. Look at the opposite bank (west side of the Paluxy River) and its sedimentary layers that are part of the Glen Rose Formation. Typically the Glen Rose Formation is about 225 feet in height. Estimate the approximate height of the Glen Rose Formation that is exposed above ground in this area.
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