Complex sentence: The North Sister possesses more dikes than any similar Cascade peak, and many dikes were pushed aside by the intrusion of a-wide plug dome that now forms the mountain's summits of Prouty Peak and the South Horn.
Split into simpler sentences: The North Sister possesses more dikes than any similar Cascade peak. Many dikes were pushed aside by the intrusion of a-wide plug dome that now forms the mountain's summits of Prouty Peak and the South Horn.