Wednesday, April 22, 2009

Wordless Wednesday

More from our geology expedition last week. This stretch of canyon is surrounded by urban sprawl, bookended on east and west by major interstate freeways and on the north and south by suburban cookie cutter housing tracts. But once you hike in, as we did heading down from a housing track, you forget the city is surrounding you.

Friday, April 17, 2009

Field Trip

My youngest son is doing Earth Science this year using a boring text book and taking a class that has some projects and labs. I decided it was time to break free of the formal studies and get out of the house to see the geology in our area. The inspiration for this is a terrific book by San Diego State professor Patrick Abbott called The Rise and Fall of San Diego. Starting with the Jurassic, each chapter describes what was happening in San Diego during each geologic period and includes field trips to see specific formations.

It was a beautiful day, so we grabbed the camera and a couple of water bottles and went hiking in a nature preserve to see some Jurassic period rocks.

The canyon floor is long and flat, a popular route for horseback riders and bicyclists. We were just about to turn around and give up hopes of finding these rocks when we rounded a bend and spotted this:

A giant boulder sticking up out of the ground. We were joking that it is San Diego's own Uluru.

Behind this monument is a small waterfall with lots of perfect boulders for climbing around and over. But what it really is, we learned today, is sedimentary layers that formed under the ocean during the Jurassic period. They've been up-ended and are lying on their sides now as you can see:

The boulders are especially cool as they are not the generic granite you'd expect, but volcanic-clast conglomerates as you can see below. The lovely green plant next to it is poison oak!

The sediment was also quite varied in color with red layers and gray layers that are apparently mud sediment. We never did find the traces of fossils, but hope to on our next outing to find some Cretaceous formations by the ocean.

That's me on the middle right , providing a bit of scale for you. I was enjoying the view while the 14yo youngster made like a mountain goat and scampered about all the boulders. All in all we hiked about 2 miles and agreed it was one of the coolest outings we've had in a while -- and the way homeschooling should be more often!