Sunday, November 05, 2006

world's longest day field trip, stop 1: dish hill

This Saturday I took a group of about 20 of my geology students on an eternally long Mojave day trip. The problem is that to get to the Mojave we have to drive 3hrs. So once you start doing things there, you don't get home until quite late.

This cactus was really cute and fuzzy looking, but I refrained from petting it. It's happily located in "desert pavement" (1st geology lesson of the day). This is basically the remains of desert sediment that hasn't been carried away by wind erosion and has the appearance of a cobblestone road.

We had a "brief" pit stop at Bun Boy in Barstow (as the hwy sign read: "Welcome to Bun Boy Country") - that ended up costing us 40min due to students not reading the first line of my "what to bring on the field trip" handout. This read "lunch" and "snacks". I think 3 people actually did that.

Anyway, here we are at (well not quite, it's the hill in the background there) "Dish Hill" a former cinder (clinker) mine - not the point of our excursion there however (in case you wanted to know, clinker was/is used to line railroad beds, sometimes road beds, and the occasional 70's style BBQ). Dish Hill, located in amongst several basaltic cinder cones, is home to a slew of olivine crystals living in lherzolite mantle xenoliths within the basaltic material. (Geology lesson #2) olivine comes from deep in the earth (mantle). Xenolith is not only one of my favourite words, but also the term for chunks of other rock picked up during the ascent of a magma from deep in the mantle that's just dying to make it to surface in the form of a volcano.

Remnants of probably a loading ramp for the clinker.

Great big olivine xenolith!

Some of the students rest and look on at the fitter souls who clambered up higher. Natuarlly I joined the climbers after taking this photo...

1 comment:

Heather said...

Very cool xenolith, very cool lava tube. Your students must LOVE you.