Craters of the Moon National Monument was less than 20 miles from our RV park in Arco, ID. It had some of the most unusual geology. I know we had just seen Yellowstone, but there are significant differences between the two areas. The large volcanoes are gone - this area has drifted away from the hot spot that now powers Yellowstone. There are no geysers or steam vents or mud pots. Even so, there has been activity (as recently as 2,000 years ago) that is relatively unchanged by erosion, given the arid climate. There were cinder cones, spatter cones, lava flows, and lava tubes all in a stark and desolate area covering 750,000 acres of central Idaho.
We learned that when molten rock reaches the surface it is called lava. When it is hot enough, it flows smoothly and it cools in smooth or ropy formations called "pahoehoe." If it cools but continues to be pushed along, it is broken into chunks called " 'a'a." Both names are Hawaiian and it is easy to see the two types being formed, in real time, there. It reminded us that when Jon was about three years old, he told everyone who asked, that he was going to be a Volcanologist - he will have to visit this place one day!
Pahoehoe
Trees have a tough life here!
The lichen is stark against the hues of the lava rocks.
Can't you just see the molten lava flowing?
'A'a and spatter cones
Can you find David in this picture?
There was a 43-degree grade hiking to the top of this cinder cone - that was a work-out in the 90-degree sun!
Lava bomb
Lots of lava bombs.
No comments:
Post a Comment