Tuesday, July 20, 2010

Craters of the Moon

In southeastern Idaho on the Snake River Plain is a large lava field and old volcanoes, Craters of the Moon National Monument.  In the distance is an eroded shield volcano. These volcanoes do not get as high as other volcanoes as the lava is near the surface and it does not have to force its way up the way that larger mountainous volcanoes such as Mount Rainer or Mount Vesuvius. The cones are much shorter and wide and the craters are smaller.

The name comes from the fact that it reminded some people of the landscape of the lunar surface.  The volcanoes and lava flows have been dormant now for about 2,000 years or so.  The area is still geologically active and part of the Yellowstone volcanic system.

The lava field is truly a unique formation. On the right is a picture of  one of many cravasses some of which extend just a few to hundreds of feet deep.

As lava flows and cools it produces cracked flats like this one pictured on the left. These fields can be wide open or short plateaus that abruptly end in lava tubes, hills broken up, or caves.

This lava mound is a twisted and contorted cracked mound. The mound shows how the lava cooled. You can see the markings of the lava when it was free flowing. Cracks and odd shapes make each of these mounds into unique natural rock sculpture.

The trees and shrubs find a niche in small openings such as the one featured on the right. Lava rock is highly rich in minerals and in soil form is known for its great crop growing from potatoes to vineyards. Many plants take advantage of these rocks for the same reasons.

To the left is a lava cave that opens at the top and descends downward. As the crust on top of the rock thins over time it eventually caves in on itself. This probably was originally a lava tube or tunnel underneath the rock before becoming this crater seen here.

To the right is a lava bridge. This thin area of pooled lava covers a crack beneath it. Going over this one was a bit tricky as I tested the weight of the rock beneath my feet. On all lava fields testing the crust is important as one can fall in to a hole or crack if they are not careful about moving around on the flow.
Finally you can see the expanse of the lava flow with the mountains in the distant background. The flow once on it seemed to go for miles and miles. The entire Snake River Plane was formed by the very forces that made Craters of the Moon National Monument. It is that other world experience without having to leave earth to see it. And unlike the moon, the lava flow supports and abundance of plant and animal life. On our way out from this trip we encountered a rattle snake. The snake is a great reminder to be careful whenever hiking in the wilderness.

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