The Cascade Range lies along the boundary between the Pacific and North American Plates so the entire chain of mountains was built through volcanic activity. Many of the peaks are the type that erupt violently, creating a crater (deeper than it is wide) and leaving a (sometimes) large field of destruction and area of ashfall. These are the violent type. A second type is called a shield volcano which undergoes periods of continuous eruption and lava flow (like Kilauea in Hawaii) building a mounded volcano covering dozens to hundreds of square miles. Over the eons, as the lava chamber empties, the mountain above it collapses in the middle creating a caldera (wider than it is deep.)
The Newberry Caldera National Monument, just south of our RV park, is an example of the latter. Friday, we drove all the way to the top of Paulina Peak to view the spectacular vistas on this
clear day. (We were able to see peaks over 100 miles in the distance.) It is a very beautiful and interesting area with two lakes in the caldera below the top where we were perched, as well as acres of lava flow (hardened into black obsidian) and pumice. We mistakenly identified it as sand, but the ranger's presentation corrected that notion and informed us visitors of the geologic history of the volcano
and the area. (How'd you think I came up with the first paragraph - duh??) There are other parts to the NM that we plan to see next week.
The Cascade Range lies along the boundary between the Pacific and North American Plates so the entire chain of mountains was built through volcanic activity. Many of the peaks are the type that erupt violently, creating a crater (deeper than it is wide) and leaving a (sometimes) large field of destruction and area of ashfall. These are the violent type. A second type is called a shield volcano which undergoes periods of continuous eruption and lava flow (like Kilauea in Hawaii) building a mounded volcano covering dozens to hundreds of square miles. Over the eons, as the lava chamber empties, the mountain above it collapses in the middle creating a caldera (wider than it is deep.)
The Newberry Caldera National Monument, just south of our RV park, is an example of the latter. Friday, we drove all the way to the top of Paulina Peak to view the spectacular vistas on this 
clear day. (We were able to see peaks over 100 miles in the distance.) It is a very beautiful and interesting area with two lakes in the caldera below the top where we were perched, as well as acres of lava flow (hardened into black obsidian) and pumice. We mistakenly identified it as sand, but the ranger's presentation corrected that notion and informed us visitors of the geologic history of the volcano and the area. (How'd you think I came up with the first paragraph - duh??) There are other parts to the NM that we plan to see next week. 
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