Lake Sakakawea

Asked September 28, 2016, 12:00 AM EDT

Hello I'm hoping maybe you could help me find out if the rock I found is a meteorite. I found along a gravel road by Lake Sakakawea.. Thank you for time any information would be greatly appreciated

North Dakota

1 Response

Here's a response from Allan Ashworth, NDSU geosciences professor:
Probably not a meteorite. It is most probably a concretion – possibly an iron carbonate (siderite). The darker brown color on the outside is iron oxide (rust) formed by exposure of the rock surface to the atmosphere. Iron concretions of this type form in shales as a result of groundwater movement and lithification (mud compacted to shale). Likely that this specimen was millions of years later eroded by a glacier from Cretaceous shale deposits beneath the ice and then transported by the glacier. When the climate changed and the ice melted out at the end of the last glaciation, about 13,000 years ago , the concretion was deposited in the Lake Sakakawea region.