Oblique view looking southwest towards Wizard Island. The distance across the bottom of the image is about 2.8 kilometers (1.7 miles).

Visible in this view are three of the four volcanoes that erupted on the floor of Crater Lake after the caldera formed 7,700 years ago: the central platform, Wizard Island, and the rhyodacite dome. The relatively subdued top of the central platform gives way at a uniform depth to steep slopes. This morphology suggests that the andesite lava that forms the platform erupted from a vent above the surface of the rising lake, flowed outward over earlier products of that vent, and broke up when it entered the lake to form talus. The break in slope marks the shoreline at the time that the last lava flowed. On the surface of the platform, broad lava flow channels and a small crater indicate that the vent was located near the platform`s northwest corner. Sinuous flows of andesite lava north of the central platform were fed by a lava channel that connects them with the crater on top of the platform.

Deeply submerged on the north flank of the Wizard Island volcano are a bench and a break in slope (S1). These are at the same depth as similar but less pronounced features on the central platform, suggesting that eruptions were occurring at both vents at the same time.

Two more old shorelines are evident on the Wizard Island volcano. One is located on its southeast flank (S2). A higher shoreline (S3) goes all around the island. Drowned subaerial lava flows connect the highest shoreline with the base of the cinder cone, showing that the Wizard Island eruptions were over before the lake filled to its present level. On the eastern flank of the Wizard Island volcano, overlapping the central platform, is the rhyodacite dome. Radiocarbon dating of the sediment above and below a corresponding ash layer on the central platform indicates that the dome erupted about 5,000 years ago. Submerged below such promontories on the caldera as Merriam Point, and Llao Rock are steep rock outcrops. Between these are talus aprons that coincide with embayments in the wall.

Source: Gardner, James V., Peter Dartnell, Laurent Hellequin, Charles R. Bacon, Larry A. Mayer, and J. Christopher Stone. 2001. Bathymetry and selected perspective views of Crater Lake, Oregon. USGS Water Resources Investigations Report 01-4046.