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Wednesday, March 30, 2016

A Geology Field Trip to the Local Mountains and Desert (yes, GEOLOGY)

I am taking a Physical Geology course at Mesa College, as a pleasant diversion from the life sciences. San Diego County is chock full of fascinating rocks and minerals and interesting land forms. More than I ever imagined!

On March 19th, we took a day-long field trip to the Laguna Mountains, and then the local desert. Terri Groth (friend and neighbor) accompanied me. About 13 people were on the adventure, including fellow classmates and the instructor, Don Barrie.

The photos below are from Canyon sin Nombre ("canyon without a name"), not far from Indian Gorge where we camped the weekend before.

This canyon was full of fascinating geological formations and types of rocks, including igneous, sedimentary and metamorphic - a little of everything we are learning about in the class at the moment.

Varied landscape near the entrance to Canyon sin Nombre. Much of the dark brown rocks are schist, a metamorphic rock.

More of the unusual swirls and strange rock patterns.

A big dike of light-colored igneous rock filling an ancient crack.

Contrast between the darker (what I believe is schist) and the felsic, light-colored igneous rock of the dike.

Some really nice gneiss (pronounced "nice"), another metamorphic rock, the result of ultra-high temperatures and pressures deep in the Earth.

Amphibolite, another metamorphic rock. 

Schist, a metamorphic rock with course grains, and foliation (a "layered" look), the result of intense pressures.

Folding in sedimentary rocks in the Olla Formation.

Dictyoptera simplicipes: A Colorful Inhabitant of Cuyamaca Woods

This beetle appears here in late winter and early spring in some years. I do not see it every year, with 2011 being the first year in which I did. In that year, quite a few were seen scattered about in Cuyamaca Woods, by myself and others. This year Gary saw one by his garden, and then the one shown below flew by us when we were on the patio at the end of the day on March 18th.

This species occurs extensively up and down the Pacific coast.

These are the first photos of live specimens that I have taken.

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A Short Diversion to Indian Gorge in the Anza Borrego Desert

From March 11 - 13 (2016), we camped with friends in Indian Gorge, a canyon in the southern portion of the Anza Borrego State Park.

We have camped there before around this time of year, and on the last trip were toasted in unusually hot temperatures (low 90s), but this year things were cooler (with a little rain on Friday night even). Some flowers were blooming from earlier rains, but it has not turned into an "epic" flower season, sadly (the El Nino rains have not materialized for southern California in the way we had hoped).

Here are a few of the highlights from this trip:

"Palm Bowl" group of native palms (Washingtonia filifera). This was one canyon south from Indian Gorge.

Desert Iguana (Dipsosaurus dorsalis), also in the canyon to the south of Indian Gorge and Indian Valley (as is the iguana below).

This one allowed a very close approach!

This very pale (felsic) granite is everywhere in the area. It has nicely formed mica embedded in it.

A pottery shard, from the earlier inhabitants of the region - the first I have seen in the Anza Borrego Desert. Indian Gorge.

Oncerimetopus nigriclavus (a small true bug with a BIG name!). In Torote Canyon, which is an off-shoot from Indian Gorge. Torote is Spanish for Elephant Tree, and a few of these trees (twhich are more abundant in Mexico) occur in this small canyon.

The Red-eared Blister Beetle (Lytta auriculata). This was the main beetle seen. NO tenebrionids (darkling beetles) were seen at all - very unusual. Possibly due to the cool temperatures.

Lytta auriculata feeding on Brittlebush.

More Lytta auriculata (MAKING more Lytta auriculata).

An ichneumon wasp, one of the few (non-moth) visitors to the black light that I set out on Saturday night.

A nocturnal mutillid (velvet ant - which is actually a wasp). At the light.

Ready to demolish Tokyo!!! Well, maybe not (it's less than a centimeter long...).
This appears to be a nymph of the planthopper Orgerius sp. Just about the most photogenic creature to appear at the light.

Another view of Orgerius sp.