Where is the triassic basin

Mudflows captured plants and animals, and over time the remains of these turned into fossils. These fossils are most likely typical of similar species that might have lived in the Durham Triassic Basin. During the Jurassic period, the stress of sea floor spreading created swarms of cracks into which magma intruded as dikes vertical or sills horizontal. In the Northeast Creek watershed basin, there are numerous diabase dikes. Another runs from Panther Creek to Lake Jordan.

Skip Nav Destination Article Navigation. Close mobile search navigation Article navigation. Volume 85, Number 2. Previous Article. Article Navigation. Research Article February 01, Google Scholar. GSA Bulletin 85 2 : — Article history first online:. Basins formed and sank, with sediments tilting down to the faults on the western edge. Rivers, lakes and wetlands formed in closed basins with no river outlets, similar to the Great Salt Lake today.

Sand layers were deposited as braided streams switch channels after major storms. Other sedimentary layers indicate an arid environment. The sides of the basin may have looked like a modern desert, while the floodplains of small sinuous rivers in the deepest part of the basin may have been vegetated like a modern jungle. Erosion ultimately deposited up to 20,, feet of sand and silt into the basin. The sandstones created from those sediments are known as "redbeds" due to the oxidized iron or rust that coats the sand grains.

The grains in the sandstone bedrock were cemented together more tightly than the Aquia Sandstone on the Coastal Plain. The valley stretches to the Bull Run Mountains, where the interstate highway goes through Thoroughfare Gap, on its way to the Shenandoah Valley.

The drop in elevation west of Centreville reflects differences in the bedrock. Differential erosion has, for the moment, excavated a shallow valley in which Leesburg, Manassas, and Culpeper are located.

The sediments in the Triassic Basin west of Centreville are eroding faster than the metamorphic bedrock of the Piedmont formations to the east, between I and Centreville. As the sediments filled in the basins, dinosaurs were walking on the land and shallow lakes. Connecticut established Dinosaur State Park to protect an extraordinary set of tracks discovered in the 's by an alert bulldozer operator, who was preparing a site for a state office building.

Some dinosaur tracks were fossilized in rocks that today are excavated at construction sites and in quarries in Loudoun, Prince William and Culpeper counties. In addition, some harder rocks formed in the basins. In some places where the crust thinned, molten magma rose from the mantle up into the Triassic basin sediments to the surface and cooled into igneous rocks known as basalt. Where the rock cooled slower and larger crystals formed, the volcanic rock is known as diabase.

Volcanic magma rose where the crust thinned and broke to create sills, dikes, and lava flows on the surface. Because the breakup of Pangea triggered formation of the basins starting in the Triassic Period, the depressions are called Triassic basins even if they continued to expand and lava continued to rise during the Jurassic Period.

Pangea cracked at the end of the Triassic Period. Lava oozed out in eruptions of "flood basalts" on the surface. The volcanism was short and intense, concentrated in just , million years. That crust melted at depth, then moved up and flowed onto the surface of the earth.

The carbon dioxide released during the flood basalt eruptions was a factor in the extinctions that define the end of the Triassic Period and the start of the Jurassic Period. Ultimately, a "spreading ridge" developed, oozing magma with the chemical composition of Mid-Ocean Ridge Basalt. The Atlantic Ocean was born, expanding into its current configuration over the last million years. Steven Spielberg highlighted the Jurassic Period when he titled his movie "Jurassic Park" because that was the period in which dinosaurs evolved further to dominate the land masses.

The moviemaker took artistic license with the geologic time scale; Tyrannosaurus rex evolved only near the end of the Cretaceous Period. Arabia and Africa starting to split apart 25 million years ago. Today, East Africa has basins formed by blocks of crust dropping down, comparable to the Triassic Basins of Virginia. Within this Formation, bedded lacustrine shales, mudstones, and sandstones preserve Van Houten cyclicity, thought to reect changes in lake level and precipitation due to Milankovitch orbital changes that affect solar radiation.

The outcrops within the Quarry are well exposed and students are encouraged to measure the stratigraphic section and critically examine and classify the rocks mostly ferroan dolomitic shales and sandstones in order to understand the lacustrine cycles.

The Solite sedimentary rocks are considered to be among the richest and most productive Triassic terrestrial sequences in the world Fraser et al. The diversity of insects is particularly significant, but plants and vertebrates are also well represented. The lack of bioturbation and exceptional preservation of vertebrate and invertebrate fossils were previously thought to reflect anoxic bottom waters in a deep lacustrine system Olsen and Johansson Recent work by Liutkus et al.