Complex sentence: On the very summit of Black Mountain, are Calera limestone rocks that originated as a seamount in the tropical Pacific about 100 million years ago and were transported to Los Altos by the Pacific Plate.
Split into simpler sentences: On the very summit of Black Mountain are Calera limestone rocks. The limestone reveals that the mountain originated as a seamount in the tropical Pacific about 100 million years ago and was transported to Los Altos by the Pacific Plate.