Big Bend National Park Report
Big Bend National Park Report 1. What is the depositional nature of the rocks in the study area and how does their lithologic compositions and sedimentary structures record changing water depths, environments of deposition, and paleogeography?
Big bend national park has complex rocks that are subsided in two seas hundreds of millions of years ago. Fossil data from the mid to Upper Cretaceous period predicts the sequence of rock strata in Big Bend National Park to be from bottom to top: limestone, shale and clay, limestone again, and sandstone and clay. The earliest layer was deposited in the relatively deep marine environment, then the ocean regressed to produce the next layer, then transgressed to produce the last. Different types of sediments are associated with varying depths of ocean water. Sediments accumulate over time and are deposited by water, air, or both.
Santa Elena:
It’s a time of mid cretaceous around 100my ago when the oldest rocks of study area start deposit. The Santa Elena formation is in the deep oceanic environment, this formation consists of the mid-Cretaceous rock types cherty limestone and marl. The rocks exist in this formation are thick, cherty limestone mixed with marly limestone. The rocks in this some finely grained rocks due to organic material from shell and inorganic calcite. The formation also contains many small marine fossils from that period. The Santa Elena Formation has been cut through by the Rio Grande to form the Santa Elena Canyon.
Del Rio:
As the oceans regressed to a shallow ocean depth, approximately 97 mya, layers of shale and clay formed the Del Rio Clay. They contain remains of marine organism and animal fossils. The bedding of Del Rio formation with shale extends all directions. The beds record the wet or dry season circle after the sediment is deposited. The lithological and paleontological data suggested that is was deposited in a shallow marine environment yellow green to yellow brown clay.
Buda
Big bend national park has complex rocks that are subsided in two seas hundreds of millions of years ago. Fossil data from the mid to Upper Cretaceous period predicts the sequence of rock strata in Big Bend National Park to be from bottom to top: limestone, shale and clay, limestone again, and sandstone and clay. The earliest layer was deposited in the relatively deep marine environment, then the ocean regressed to produce the next layer, then transgressed to produce the last. Different types of sediments are associated with varying depths of ocean water. Sediments accumulate over time and are deposited by water, air, or both.
Santa Elena:
It’s a time of mid cretaceous around 100my ago when the oldest rocks of study area start deposit. The Santa Elena formation is in the deep oceanic environment, this formation consists of the mid-Cretaceous rock types cherty limestone and marl. The rocks exist in this formation are thick, cherty limestone mixed with marly limestone. The rocks in this some finely grained rocks due to organic material from shell and inorganic calcite. The formation also contains many small marine fossils from that period. The Santa Elena Formation has been cut through by the Rio Grande to form the Santa Elena Canyon.
Del Rio:
As the oceans regressed to a shallow ocean depth, approximately 97 mya, layers of shale and clay formed the Del Rio Clay. They contain remains of marine organism and animal fossils. The bedding of Del Rio formation with shale extends all directions. The beds record the wet or dry season circle after the sediment is deposited. The lithological and paleontological data suggested that is was deposited in a shallow marine environment yellow green to yellow brown clay.
Buda