Oregon's famous Crater Lake not 1,000 years old

Science News Letter
Medford, Oregon
December 29, 1934

Blue Crater Lake, in the national park of that name, at last has divulged the secret of its age. Not all at once, however. A few facts it revealed to the geologist, a few more to the student of tree rings, others to the engineer. Putting two and two together, these various specialists have come to the conclusion that Crater Lake is young, not yet 1,000 years old.

Crater Lake lies in a great volcanic crater, and from the floor of this crater rise two islands, results of the last puffs of volcanic action. One of these, Wizard Island, is a small volcano. On its shoulders it bears a mantle of tree life, the first that ever grew there, according to scientists. By counting the annual rings on cores of wood bored out of these trees, Dr. W.G Vinal has found some of them to be nearly 800 years old.
 

Since observations by scientists and others of various volcanoes show that only a few years elapse between the cessation of eruptions and the growth of plant life on volcanic slopes, it is estimated that the probable cessation of volcanic activity on Wizard Island occurred some 900 to 1,200 years ago. Since the rocks of the island do not show the characteristics of lava that has flowed into or through water, it is believed that the lake is younger than the island, or well under 1,000 years.

It is estimated that the lake, which now has an average depth of 1,500 feet, was built up to its present level over a period of 730 years. This estimate is based on the average evaporation of 50 inches a year, and an average of 10 inches of precipitation lost through seepage. These figures are based on an average of rainfall and evaporation equaling the average of the past 50 years.