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

Uploaded: 29 Apr 2020
Last Updated: 20 May 2020

1.72 gigapixels
61,260 x 28,028 pixels
204.2 in X 93.4 in at 300dpi
4 pixels per inch

The Swift Dam area northwest of Depuyer, Montana, showcases Sever-style mountain building of the Cordilleran fold-and-thrust belt. Here, Mississippian carbonates have been arched eastward along asymmetric anticlines, and thrust over Cretaceous black shales originally deposited in the Western Interior Seaway. Notice how the limestone strata are horizontal on the left, and then begin to nose over (get steeper) to the right. To get a view of the "nose" of the fold, see this gigapan: https://viewer.gigamacro.com/view/jj1vfpBQiP4WA7mZ