Yellowstone: Day 2
Northeastern YNP and the Grand Canyon of the Yellowstone

columnar jointing Even though Thursday morning dawned grey and drizzly, we got up bright and early for a short hike to see columnar jointing and an outcrop that was evidence of the bimodal magmatism in the park area. Left Columnar jointing caused by cooling cracks in a basaltic flow. Right The polygonal pattern of the jointing is evident from the top of the columns. columnar jointing

During the Yellowstone area volcanism, trees were buried in deep layers of pyroclastic ashflow. The trees were preserved upright in the rock in their original orientations. Here, a tree that has remained as the surrounding tuff weathered away. petrified tree

Heart Mountain detachment fault Just west of the park boundary is an extremely shallow and extremely long-running fault, or decollement. The Heart Mountain Detachment Fault is visible in this picture as it cut through a weak limestone layer (the white line in the rocks.

Of course, no field trip would be complete without some van trouble. Fortunately, there was only a funny smell that turned out to be nothing. van trouble?

Eric discusses river cutting Lower Falls Chris hanging from a tree
After driving around all day, our last stop made up for it all--the Grand Canyon of the Yellowstone. This is an area where the Yellowstone River has cut a deep canyon for itself. The yellow- tinted rhyolites that gave the river its name line the canyon walls. Above right Eric discusses river downcutting. Above center the Lower Falls, one of two spectacular drops in the river caused by the caldera rim. Above right Chris contemplates the scene while hanging from a tree. Below Peter and Rachel for scale against the yellow canyon walls.
Peter and Rachel at the Grand Canyon of the Yellowstone


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Last Modified: March 10, 1998