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_2170741.JPG - This well rounded boulder is about 12 inches across. The camera lens cap is 3.5 inches wide. Have your final guess yet? It turns out these cobbles and angular clasts are DROPSTONES. They were pieces of rocks plucked into the base of a glacier. The glaciers calved into the sea, created an iceberg, and these stones were dropped onto the muddy seafloor as the rafted chunks of ice melted. Some dropstones even have preserved the "splatted" mudstone compression rings that records the rock's impact with the mud. The catch??? Paleomagnetism places the formation of these rocks within 10 degrees of the equator. So how do glaciers & the equator mix? Reference the snowball earth in your textbook during the late proterozoic.

This well rounded boulder is about 12 inches across. The camera lens cap is 3.5 inches wide. Have your final guess yet? It turns out these cobbles and angular clasts are DROPSTONES. They were pieces of rocks plucked into the base of a glacier. The glaciers calved into the sea, created an iceberg, and these stones were dropped onto the muddy seafloor as the rafted chunks of ice melted. Some dropstones even have preserved the "splatted" mudstone compression rings that records the rock's impact with the mud. The catch??? Paleomagnetism places the formation of these rocks within 10 degrees of the equator. So how do glaciers & the equator mix? Reference the snowball earth in your textbook during the late proterozoic.

Date: 2/17/08 3:02 PM

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