Here are a few of the things he gave us an opportunity to see.
First the basic orientation of the Santa Catalinas front range.
The slope is about 23 degrees, which was the angle at which the rock gave way or faulted as it was pulled in the formation of the basin and range topography. As the area stretched a whole set of mountains now all the way over by Saguaro West formed the Tucson basin. The basin dropped about 10,000 feet. Five thousand is now full of sediment from the erosion process and helps to form the aquifer that has supplied Tucson with water. See the visual aid . The Tucson Mountains are to the left, the basin in the middle, and the Santa Catalinas to the right. The general orientation or the pull was south by southwest.
He tugged on a towel on his display table to demonstrate how the pull or stretch develops little parallel humps and valleys, thus the parallel Bear, Rattlesnake and Sabino Canyons.
Faults caused some formations to slip by each other producing parallel scratches and shiny surfaces called Slickensides. Here Bruce is showing us how they moved.
A look at the eroded stream channel of Rattlesnake Creek shows how deposits of various sized boulders and gravel can show the strength of floods down the canyon at various times in geologic history.
|Globe Mallows near current bottom of Rattlesnake Creek|