Crater Lake

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, Universityof Wisconsin - Green Bay

---

The map below was created from 1:250,000 elevation data and the contours area bit generalized. Contour intervals are 100 meters and yellow denoteselevations of 2000-2100 meters. 

	Any route to Crater Lake involves a pretty but monotonous drive through a green tunnel.
	The standard postcard view of Crater Lake

Below, panoramas from near the Visitor Center. Some foreground details havebeen changed for visibility.

	The Visitor Center
	Crater Lake Lodge
	The cliff behind the lodge. Note the dipping layers.
	View south down the valley from the lodge.

Below: a panorama looking southeast from the lodge, showing a remnant of thesurface of Mount Mazama on the ridge. Note the outward slope and also note thatthe layers in the cliff dip outward parallel to the ridge crest.

	View east along the south shore of Crater Lake
	View southwest showing Mount McLoughlin. Mount McLoughlin is one of the less well known of the Cascade volcanoes because it has not been historically active and because it is not easily accessible. Nevertheless it is 3000 meters high and has one of the most perfect cones in the Cascades.

Clark's Nutcrackers

Below: a panorama of the east and north sides of the lake.

	West end of Crater Lake. Llao Rock is the high cliff
	View east across the summit of Wizard Island. Note the crater on the top of Wizard Island and the truncated U-shaped glacial valley on the far side.
	Immediately south (right) of the scene above is another truncated U-shaped glacial valley.
	Llao Rock is a large lava flow that filled a valley and spread out on either side. Collapse of Mount Mazama created a nice cross-section. The high cliff is the filled-in valley and the "wings" on either side of the cliff are the portion of the flow that extended beyond the valley.
	Wizard Island.
	Llao Rock
	View west from the rim
	Looking north toward Mount Thielsen. The empty brown area is the Pumice Desert.

It's not immediately obvious why the Pumice Desert is so devoid of trees, butit offers one supreme advantage. It is the most convenient vantage point forviewing the broken stump of Mount Mazama.

Below: a reconstruction of the possible appearance of Mount Mazama before itscollapse (Amazingly, there was a road there at the time! Even the trees were inthe same place. And you know there are readers who will take thatliterally!) The view was createdby combining the view above with the summit of another Cascade Range volcano.

Summit of Mount Thielsen from the Pumice Desert.

Reconstructing Mount Mazama is inherently speculative. A number of geologistshave speculated that the volcano had two summits since the drainages on thesoutheast side of the lake do not radiate from the same center as those on thewest. The reconstruction above starts by reconstructing contours around the lakerim and then building upward using a typical slope for a stratovolcano. Thereconstruction above shows a single, possibly dissected or landslide-collapsedpeak, but it's not hard to picture a main cone to the west and a lower parasiticcone to the east. The reconstruction below shows a two-summit interpretation.The height is about 3400 meters or just over 11,150 feet, pretty close to thevalue estimated above. A slightly different slope could easily raise or lowerthat by 300 meters (1000 feet).  Mazama was definitely no Shasta or Rainierbut it could easily have been equal to Mount Lassen, Mount Hood or Mount Adams.The lake shore (black) and roads are shown for reference.

---

Return to Historic Sites Index
Return to Virtual FieldTrips Index
Return to Professor Dutch's Home Page

Created 7 April 2003, Last Update 06 June 2020