Friday Field Foto #21: Climbing ripples
Today we are gonna look at some ripple cross-laminated sandstone. More specifically these are called ‘climbing ripples’, or sometimes you may see this sedimentary structure referred to as ‘ripple drift’. These show up particularly nice in this photo because of the light-dark contrast of the sandy vs. muddy laminae.
Climbing ripples record both migration (lateral) and aggradation (vertical) of the bedform. In this example note the very prominent ripple set in the middle section of the photo nicely showing the ‘climb’ from left to right. Different angles of climb represent different ratios of migration and aggradation. Climbing ripples are commonly interbedded with or grade upwards into wavy laminae.
This image at left is a classification of types of climbing ripple-laminated structures based on the angle of climb (click on image for larger view; click here for source of image).
Climbing ripples are most commonly seen in river and turbidity current deposits, typically in sub-environments of high rates of deposition from decelerating flows.
On a side note, Dr. Lemming has pointed out a new geology-related blog out there. It’s called All of My Faults Are Stress Related and looks to be a nice addition to the geoblogosphere. I have a few more new links over there on the sidebar that i’ll post about soon.
I also have an updated album of Patagonia photos you can check out here. The above image is from that collection.