Saturday, August 08, 2015

Geological time

Had a chance to hear a talk for the docents of Torrey Pines Nature Reserve this morning, about the geology of the region - and with a new theory about why our rare trees, the Torrey Pines, are indigenous only to a little patch of North San Diego County and an island way north off the coast of Santa Barbara. The talk began with this gorgeous seventy-odd-year-old physiographic map. One forgets San Diego is full of mesas of sea sediment carved by rivers, and didn't know that a kink in the Rose Canyon fault is the reason the coastline is interrupted by Mount Soledad, Point Loma, and San Diego Bay. And Santa Rosa Island may have started out nearby, pushed and rotated northwest by tectonic activity of just the past dozen million years. Funny how going home to the place I grew up connects me with the deepest scales of time...

Walking below the Torrey Pines cliffs today I noticed a recent rockfall, from a thin sulfur-yellowish layer about half-way up. Among the rubble this petrified shell! My father reckons it's 45 million years old. See?

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