When: 7:00 PM, Tuesday, 8 March 2016

Where:  Orca Books (509 East 4th Avenue, Olympia, Phone 360.352.0123)

Our December Topic Is:  Using Geographic Information Systems (GIS) to Take a New Look at the Mima Mounds

The formation of the Mima-type mounds has been a puzzling and contentious topic.  This study started as an idea for an undergraduate GIS lab.   I was interested to see if I could use ArcGIS tools designed for hydrology analysis to classify the Mima mounds.    High-resolution elevation data made this possible and I was able to identify over 27,000 mounds in five different prairies in southern Thurston County.  A dataset of this size allowed subtle, but statistically significant, morphological and spatial characteristics to be identified.  Mound area, height, volume, and density were shown to vary locally and regionally.  The most significant finding was that the mounds are not symmetrical, when viewed collectively they are elongate and have a preferred orientation.  That orientation differs depending on the prairie and the general gradient of the outwash terrace that they formed on.  In some prairies the elongation is east-west and in others it is north-south.  This preferred orientation argues against the bioturbation (and seismic vibration) theory.

About the Speaker:

Ken Tabbutt, Ph.D., a faculty member at The Evergreen State College, has taught interdisciplinary geology programs for the past twenty years.  He frequently incorporates GIS in his classes that generally focus on environmental geology, hydrogeology, and landscape processes.

Next Month: El Nino and the Madden-Julian Oscillation