Middle Sister also known as "Hope," is a stratovolcano consisting primarily of basalt but also has erupted andesite, dacite and rhyodacite. Last erupting approximately 50,000 years ago, it is considered extinct. The mountain's form is that of a cone which has lost its east side to glaciation. The Hayden and Diller glaciers continue to cut into the east face while the Renfrew Glacier is located on the northwestern slope. The large but retreating Collier Glacier descends along the north side of Middle Sister and cuts into North Sister's west side.
Middle Sister is the smallest and most poorly studied. It is also the middle in age, but only somewhat older than South Sister, with the most recent flows dated to 14,000 years ago.
Read more about this topic: Three Sisters (Oregon)
Famous quotes containing the words middle and/or sister:
“There is singularly nothing that makes a difference a difference in beginning and in the middle and in ending except that each generation has something different at which they are all looking. By this I mean so simply that anybody knows it that composition is the difference which makes each and all of them then different from other generations and this is what makes everything different otherwise they are all alike and everybody knows it because everybody says it.”
—Gertrude Stein (1874–1946)
“Before any woman is a wife, a sister or a mother she is a human being. We ask nothing as women but everything as human beings.”
—Ida C. Hultin, U.S. minister and suffragist. As quoted in History of Woman Suffrage, vol. 4, ch. 17, by Susan B. Anthony and Ida Husted Harper (1902)