News from the Geoblogosphere
New from Snet:
, a new tool to create lithological/sedimentological logs online..
Blog post recommendation
Geo-challenge: What’s behind this curious beauty?
I found these beautiful and mysterious sculptures in
Goblin Valley State Park
in southeast Utah, on the opposite side of the main ridge from the goblins (below).View from parking lot. Goblins (technically
) eroded out of the Entrada sandstone – actually a mix of sandstone, siltstone and shale (cliffs in background).Mid-Jurassic Entrada sandstones, siltstones and shales – once tidal flats and coastal dunes. Pale-colored layer above is the Curtis Formation, also Jurassic. I took the Goblin’s Lair Trail around to the east side of the ridge (above). In a large alcove, I found walls of Entrada sandstone covered with what looked like mud that had run down from above.My camera had color issues in the shady alcove. For reasons now forgotten, I took no photos of the entire alcove. Here’s a Google Earth view instead. The “mud sculptures” were on north- and northwest-facing walls.Click on image to view details.
Back at the car, I checked accounts of Goblin Valley State Park in two geology guidebooks. They described depositional and erosional features in the park, both ancient and modern: tidal cross-bedding, remnants of tidal channels, dune cross-bedding, ripple marks, talus, stream-bed ripples, gilgai (popcorn-textured soil), microbiotic crust, intermittent stream channels, and of course hoodoos/goblins. But neither book mentioned mud sculptures on alcove walls.
What are they? Are they depositional, erosional, both? All attempts at clever googling have failed. Can you help? If so, please Comment. I seek enlightenment.