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Hanksville, unfold, Utah, geology, ezValidator, slokkert

Outcrop Jurassic Summerville Fm, along S276, Mile 19 south of Hanksville, Utah. Playa deposits with small-scale compressional overthrust faulting and folding in response to gravitational sliding in between diapiric volcanic intrusions. Photo Evert van der Graaff.

1. Unfolded with strain display

The movement is largely rotational.

Strain display, purple compression, blue dilatation from original to unfaulted. Colour scale 10% (light colour), 20% (dark colour).

The strain accumulates above and below the zone of interest between the two unfolded horizons.

2. Mattress on my driveway

This is a piece of foam mattress propped up between two rocks on my driveway.

The black lines on the mattress indicate a center line for the unfolding, and a set of reference lines orthogonal to the center line.

3. Mattress unfolded

The mattress is unfolded for the center line.

The angles between the vertical lines and the center line are unaffected.

There is very little deformation around the unfold line over the extent of the mattress. But the bricks away from the mattress are compressed at the top and dilated at the bottom.

4. Mattress unfolded with strain display

The mattress is unfolded for the center line.

Strain display, purple compression, blue dilatation from original to unfolded. Colour scale 10% (light colour), 20% (dark colour).

There is very little deformation around the unfold line over the extent of the mattress. But the bricks away from the mattress are compressed at the top and dilated at the bottom.

Utah, Hanksville: folded playa deposits

Notes: the strain overlay below shows that there is little deformation within the zone of interest but there is deformation outside the zone of interest. A further example illustrating this with a piece of foam mattress is given below.