Craters of the Moon

by William Mclaughlin September. 21, 2015 1769 views

We spent two days at Craters of the Moon National Monument and Preserve near Arco, Idaho, earlier this week. The Monument contains over 400 square miles of lava, which erupted from a fissure as recently as 2,000 years ago. As the North American Plate passed over a hot spot, this fascinating place was formed. It's the same hotspot that created Yellowstone.

Walking along one of the interpretive trails, we got to see some of the lava up close.

Depending upon how the lava flowed, different types of rocks were formed. ALL of these rocks are lava from the same source.

When small bits of lava pile up, they form a cinder cone. This one had an “official” trail. Those are people walking along the ridge … just to give you a sense of scale!

These spatter cones formed when the lava output slowed and sort of gurgled and plopped rather than spewed.

Eventually even rock breaks down, and there are plenty of minerals and nutrients in lava rock to support loads of vegetation.

The extra branches on this tree give it the name Witch's Broom. This is a pine tree that was living with mistletoe, which is a parasite. The tree's response to the mistletoe is to send extra nutrients to the affected area, causing these fascinating branch formations. The tree died years and years ago when the park managers of the time decided mistletoe “infected” pine trees were unsightly and needed to be eradicated. They don't do that any more. Both the pines and the mistletoe are native to the area, and they're now being left alone.

Our next stop will be Yellowstone! See you there!

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