Phantom Ship and Crater Lake

January 06, 2012

Crater Lake Caldera

Photographer: Marli Bryant Miller; Marli's Web site
Summary Author: Marli Bryant Miller

January 2012 Earth Science Picture of the Day Viewer's Choice

Crater Lake, seen above, is now the deepest lake in the United States at 1,932 ft (589 m). It was formed during the cataclysmic eruption of Mt. Mazama about 7,700 years ago. The eruption expelled some 12 cu mi (50 km3) of material. This volume was enough to cause the mountain to collapse downwards into the magma chamber to form the caldera. The lake receives its water supply entirely through precipitation. As a result, it contains very little suspended sediment, making its water unusually clear and blue. Studies that employ a black and white "secchi disk" indicate that its visibility frequently exceeds depths of 120 ft (37 m). This clarity and water depth causes most wavelengths of light -- except for very dark blue -- to be absorbed. The caldera walls contain layer upon layer of earlier lava and pyroclastic flows to indicate that Mazama had a lengthy volcanic (and at times explosive) history before the climactic eruption. Phantom Ship, the small rugged island near the center of the photo, consists of 400,000-year-old andesite, the oldest rock within the caldera. Mt. Thielson, an eroded volcanic neck, appears in the left background. It fed a 300,000-year-old shield volcano, the profile of which is visible on the far skyline. Photo taken August, 2007.

Photo details: Camera Maker: Canon; Camera Model: Canon EOS 30D; Focal Length: 19.0mm; Aperture: f/11.0; Exposure Time: 0.125 s (1/8); ISO equiv: 100; Exposure Bias: -1.67 EV; Metering Mode: Matrix; Exposure: program (Auto); White Balance: Auto; Flash Fired: No (enforced); Orientation: Normal; Color Space: sRGB Profile; Software: Adobe Photoshop CS3 Macintosh.