Geopuzzle #11

Spot (and explain, if you can) the differences.




It’s not much of a hint to say that the last one is quite difficult – but the last one is quite difficult.
Update: Click through for the answer.

Categories: geopuzzling

Comments (6)

  1. I’m going to take a wild guess. The top one has asymmetric ripples formed in a stream dominated environment, the centre one symmetrical ripples caused by shallow water waves and the down one is ripples deposited by wind blown sand/silt.

  2. BrianR says:

    I agree w/ Lost Geologist that the upper and middle look like asymmetric and more symmetric, respectively. Additionally, the crests on the upper one are straighter relative to middle, which are getting towards lingoid.
    The bottom photo has two layers of slightly different directions superimposed on the outcrop. But, in terms of general characteristics, the ripple marks look more like the upper photo than the middle. But, I’m probably missing something obvious.

  3. Mel says:

    I agree. In the lower photo the crests of the ripples seem much longer than the top two photos (laterally uniform current), it’s also lighter in color with a red hue (oxidizing environment, less clay), and there is a ~45 degree change in current direction in a small vertical distance (short duration current direction changes). Without seeing inverse grading on the ripples, I’d say the bottom photo is eolian in origin as well. I can’t wait to hear the answer!

  4. The last one looks like my kitchen floor…

  5. ScienceWoman says:

    The bottom photo ripples are also much more laterally continuous, which makes me think wind. Are all of these in a close proximity? If so, you could have a stream entering an ocean with a beach. I had a field trip to a site like that once, and it was really cool to see all of the ripple forms close together. Also, any ripples in the sand in the background in photo 1?

  6. BrianR says:

    so … are ya just gonna leave us hangin’?