Facts about geologic dating
Facts about geologic dating - 996 online swingers couple dating site
Their search took them to a badland area near Landslide Butte, a prominent landform near the Milk River to the east of here.Stebinger named the sandstone and mudstone rock unit the Two Medicine Formation, and determined that it was nearly 2000 feet thick, representing a geological time span from 74 to 80 million years ago.
These rocks form most of the outcrops along the highway from east of Libby to the Idaho border.
This gigantic rift valley stretches all the way from the British Columbia-Yukon border south to the St. The high mountains on both sides of the trench are composed of Precambrian sedimentary rocks that were deposited in an inland sea more than 1.4 billion years ago.
But the mountains themselves did not begin forming until about 110 million years ago when the North American tectonic plate overrode the Pacific plate far to the west.
Algae mats often trapped fine particles of calcium carbonate to form rounded structures called stromatolites.
Near the river below Swinging Bridge are wonderful examples of stromatolites.
In this area, the rocks are slightly folded so that the river cascades over the inclined hard quartzite beds in the stair-step-like falls.
Individual folds may be seen in the north-facing road cut just south of Highway 2, southwest of the parking lot. These folds resulted from east-west tectonic compression that caused north-to-south trending folds and faults throughout western Montana about 50 to 100 million years ago.This collision shoved enormous pieces of the earth’s crust eastward, where they rode up and over the rocks to the east along thrust faults and stacked up “like shingles on a roof” to create the Rocky Mountains.Then, about 55 million years ago, the tectonic setting changed and the earth’s crust in this region began to pull apart, reversing the movement on some of the “shingles” and dropping them back down along normal faults.The hills usually occur in groups called a drumlin field.[ BACK TO TOP ] In 1912 Smithsonian geologist Eugene Stebinger and paleontologist Charles Gilmore came to Blackfeet Country looking for dinosaur remains.The surfaces of the rocks often display mud cracks, ripple marks, and the spatter marks of raindrops.