6.4C| Calderas and the Story of Crater Lake

Overview

In addition to volcanoes, volcanic activity makes other remarkable and unique landform features. One of the most spectacular are calderas. Roughly speaking, a caldera is a super-sized crater made through extraordinary circumstances. During gigantic eruptions, usually of composite cone volcanoes, the volcano may lose sufficient magma from its magma chamber to make it hollow. Unable to support its weight, the volcano collapses, producing a vast, deep pit. These pits can fill up with water to create large, deep lakes, such as Lake Toba in Indonesia and Crater Lake in Oregon. Crater Lake is one of the deepest and clearest lakes in the world: nearly 2000 feet deep, with water so clear that one can see a reflective object up to 100 feet deep.  It was one of our first wild areas designated a National Park due to its natural beauty. Below are a couple of photos from my visit to Crater Lake.  Note, in particular, how blue the water is - a result of the remarkable clarity of the lake.  You might also notice a cinder cone that grew from the caldera floor from residual magma in the magma chamber after the caldera-producing eruptions.   

Crater Lake.

Crater Lake with cinder cone and professor.

Instructions

Read Mount Mazama and Crater Lake: Growth and Destruction of a Cascade Volcano and answer the following questions. Read each question carefully and choose or compose the best answer. You have three attempts and no time limit.  

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Time Needed

Approximately 45 minutes. 

Learning Objectives

• Students can describe the eruptive and physical characteristics of different types of volcanoes
• Identify and describe how calderas form
• Explain why some volcanoes explode while others do not