How was the Tapeats Sandstone formed?
The Tapeats Sea at the late Cambrian ceased to deposit more Muav Limestone, and a period of erosion ensued, a deposition unconformity. The Tapeats Sandstone was laid upon the Vishnu Basement Rocks, after an unconformity of erosion, the Great Unconformity.
When was the Tapeats Sandstone formed?
Tapeats Sandstone (~525-515 Ma) The Tapeats Formation consists of medium to coarse-grained feldspar and quartz-rich sandstone beds with quartz-rich conglomerate near the bases (Middleton and Elliot, 2003).
How was the Coconino sandstone formed?
The Coconino Sandstone formed as the area dried out and sand dunes made of pure quartz sand invaded a growing desert some 260 million years ago (see 6b in figure 1). Today, it is a 375 to 650 ft (115 to 200 m) thick golden white to cream-colored cliff-former near the canyon’s rim.
How old is the Tapeats Sandstone layer?
about 545 million years old
Tapeats Sandstone – This layer averages about 545 million years old and is composed of medium-grained and coarse-grained sandstone. Ripple marks formed by ocean waves of an early Cambrian sea are common in the upper layer.
What fossils are in Tapeats Sandstone?
Fossils to be found in this layer consist of marine animals such as trilobites and brachiopods. Tapeats Sandstone – This layer averages about 545 million years old and is composed of medium-grained and coarse-grained sandstone.
What are the proposed depositional environments for the Tapeats Sandstone?
The depositional environment of the Tapeats Sandstone is interpreted to have been an intertidal marine shelf bordered by sandy dunes (“National Park Service”).
What color is Tapeats Sandstone?
brown
A brown, distinctly layered cliff. The Tapeats is a massive cliff-forming unit of brown sandstone. Much of the sand is very coarse-grained, often pea-sized or larger, and some grains are beautifully colored–my students call this the M&M conglomerate.
What is Coconino Sandstone made of?
The Coconino Sandstone is typically buff to white in color. It consists primarily of fine well-sorted quartz grains, with minor amounts of potassium feldspar grains deposited by eolian processes (wind-deposited) approximately 275 million years ago.
What kind of landscape formed the Coconino Sandstone?
dry desert landscape
The Coconino is an eolian deposit, meaning it records dunes flowing across a dry desert landscape. It is very clearly an eolian deposit, displaying classic wind-blown features such as frosted sand grains and large crossbedding formed from dunes rather than currents.
Is Tapeats Sandstone metamorphic?
The material for the Tapeats was derived from the underlying Precambrian granites and metamorphic rocks found in the region.
What rock type is Tapeats Sandstone?
The Cambrian Tapeats Sandstone rests unconformably on the Proterozoic Vishnu Schist. This unconformity represents a billion-years of missing geologic time, hence it’s referred to as The Great Unconformity.
Where is Coconino Sandstone found?
Arizona
Coconino Sandstone is a geologic formation named after its exposure in Coconino County, Arizona. This formation spreads across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah.
What is Tapeats Sandstone made of?
Tapeats Sandstone (averages 545 million years old) – This formation is made of cliff-derived medium- to coarse-grained sand and conglomerate that was deposited on an ancient shore (see 3a in figure 1). Ripple marks are common in the upper members of this dark brown thin-bedded layer.
What is Cambrian Tapeats Sandstone?
The Cambrian Tapeats Sandstone is the lower geologic unit, about 230 feet (70 m) thick, at its maximum, of the 3-member Tonto Group. It is famous for being the highly-resistant mostly-horizontal unit above the 1,000 my (1 by), Great Unconformity expressed areally in the Grand Canyon of Arizona; also in other areas of Arizona and adjacent Nevada .
What is the Tapeats unit?
The Tapeats unit is the bottom member of the Tonto Group, a typical marine transgression series of sandstone- (conglomerate)- shale-limestone, all part of a paleo sea, initially adjacent to land, the source of the Tapeats rocks- (conglomerates) and sand; (a regressing sequence has the reverse order).
How old is the Tapeats?
The Tapeats is between 500 and 550 My old, and contains a few diagnostic trace fossils such as Correphioides and Diplocraterion over the Mogollon Rim, and some trillobite trackways in the Grand Canyon. From Wikipedia Tonto Group