North Sister, also known as "Faith," is the oldest and most eroded of the three, with towering rock pinnacles and glaciers. It has not erupted since the late Pleistocene. It is the most dangerous climb of the Three Sisters, due to its level of erosion, and thus rockfall.
North Sister is a shield volcano consisting primarily of basaltic andesite and is estimated to have last erupted over 100,000 years ago and is considered extinct. The North Sister possesses more dikes than any similar Cascade peak. Many dikes were pushed aside by the intrusion of a 300 meter wide plug dome that now forms the mountain's summits of Prouty Peak and the South Horn. The remainder of the peak is chiefly loose debris held in place by the dike system.
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Famous quotes containing the words north and/or sister:
“Come see the north wind’s masonry.
Out of an unseen quarry evermore
Furnished with tile, the fierce artificer
Curves his white bastions with projected roof”
—Ralph Waldo Emerson (1803–1882)
“Let me see, what am I to buy for our sheep-shearing feast? Three pound of sugar, five pound of currants, rice—what will this sister of mine do with rice? But my father hath made her mistress of the feast, and she lays it on.”
—William Shakespeare (1564–1616)