Existing comment:
Park Avenue:
The sheer walls of this narrow canyon reminded early visitors of buildings lining a big city street. Rising majestically, these geologic "skyscrapers" tell the story of the Entrada Sandstone.
Entrada Sandstone began forming more than 150 million years ago as tidal flats, desert, and beach deposits. Over time, layers of rock, perhaps a mile thick, covered these deposits. Tremendous pressure from these rock layers compressed the buried sand into sandstone and cracked it. Erosion then removed the overlying rock layers and the Entrada began to weather.
With the past two million years, erosion of the cracks in the Entrada has left vertical slabs like the rock wall to your right. These slabs, called fins, are the first step in arch formation. |