By: magic-gigapans
Image: Robin Rohrback, Mid-Atlantic Geo-Image Collection
License: Creative Commons Non Commercial ⧉

Uploaded: 4 May 2020
Last Updated: 26 Jun 2020

338 megapixels
16,012 x 21,112 pixels
53.4 in X 70.4 in at 300dpi
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Massive clast-poor diamictite from the Ulveso Formation in east Greenland. The sandy deposits in this otherwise massively bedded sample are interpreted as meltwater-washed horizons deposited in a fluctuating subglacial environment. The sandy horizon was probably originally deposited in cavities exposed by melting basal ice during a period of increased warmth and sediment discharge. This deposit was subsequently eroded (sheared) by basal ice contact during glacial flow. Sheared reactivation surfaces in the sample suggest that the glaciers were at least partially wet-based. Sample is 11.7 cm across at its widest point. This sample is from the Snowball Earth Educational Rock Sample Suite, and comes courtesy of Paul Hoffman, Harvard University; Eugene Domack, Hamilton College; and Timothy Fox, Hamilton College. For more information on the Snowball Earth Educational Rock Sample Suite, visit http://www.snowballearth.org/samples.html