Monday, June 17, 2013

Geo 365: June 17, Day 168: Radial Jointing

About 2/3 of the way up this cliff, you can see a large area of radial joints, or columns, if you prefer. This is at Yaquina head, north of Newport, Oregon, at the northeast end of the parking lot at the visitor center there. The rock is Columbia River Basalt, and this is one of a number of areas where those Miocene flows reached the area of the present coastline. The radial jointing above probably represents a lava tube or conduit that cooled without draining. The joints formed perpendicular to the cooling surface. Since that was cylindrical, the fractures converged toward the middle of the tube.

Photo unmodified. March 7, 2012. FlashEarth location.

No comments: