Sunday, April 5, 2015

Geo 1095: April 5, Day 825: Parking Lot Puzzle

The parking lot at Fish Lake is bordered with blocks of basalt to keep vehicles in the intended area. This one, as I recall, was to the right (south) if you're facing the restroom, maybe two or three "blocks" away from that path. Here's the puzzle: there are a number of similar features in this photo which fairly consistently indicate what the direction of "up" was when this block of lava cooled. What are those features, how did they form, and what direction was "up" at the time? Answers in comments, and I'll post my own if a good one isn't offered before I get ready to go home tomorrow.

Followup, April 6, 4:06 PM:
In the above annotation, I've outlined six "lava drips," or as Hollie, in her correct guess in the comments described them, "lavacicles." The outlines are solid lines, and I've roughly bisected them with dotted arrows, which point in the direction that was down when the drops solidified. There's some variation, but all the drops point up and to the left, so "up" was down and to the right. As Hollie noted, this was likely the roof of a lava tube, or at least a large bubble in this flow.

Photo unmodified. October 9, 2014. FlashEarth Location.


Hollie Oakes-Miller said...

"Lavacicles" indicates that the surface that your lens is on was the ceiling of a lava tube.

Lockwood said...

Bingo! (Some kind of void, at least.)