A recent co-worker reminded me of some of my drives through the local area. I had forgotten, but realized there are these earthen “ribs” around here, most prominent in some of the links below. I suspect they’re from ancient volcanic activity, but is is there a name for them? How were they formed? Set your Google Maps to “Terrain View” and zoom out. . . you’ll see what I mean.
i’m going to delete my stupid speculation on what they might be and just give my links to the third one and the first one from Google Street view which provide a more up-close view of them. The third one definitely doesn’t look like glacial activity to me, but I’m not 100% sure on the first and I can’t find a good up-close view of the second.
Looks like that’s it, as wikipedia’s entry on dikes has a picture of one of these near Shiprock! For some reason I thought that dikes were always vertical.
I think it is–I can remember seeing some granite dikes in Nevada, out towards the Testing area, and I’ll take a look while I’m out there this week. I’m simply more familiar with New Mexico lately.
Dykes can be subvertical, the defining feature is that they cut across existing geology like sedimentary beds or other conformities. Just like sills don’t have to be horizontal, just parallel to existing bedding. Note that the Wiki illustration of the difference even uses a subvertical dyke.
Under ‘Map View’ there ought to be three little bars in the top left of your screen for “Menu.” Click that, and the dropdown should have “Terrain” under ‘Satellite.’
Not really. “Basin and range” refers to topography on much larger scales. The basins and ranges, as the article says, appear to be due to lithospheric extension in the region. Basically the crust has been stretched out, resulting in faulting with upthrust ranges and downthrust basins. The ranges run parallel to one another, but are not straight lines, and are thousands of feet higher than the basins.
These are clearly volcanic dikes, which mostly are a few tens of meters in height. Now volcanism in the region is related to its tectonic history, so there is a connection. But these features are much much smaller than the “ranges,” and are due to a different geological process.
In fact, there aren’t any typical ranges visible near these features. The classic Basin and Range topography is mostly seen in Nevada and western Utah.
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