Glacial Lake Great Falls - Highwood Mountains Expedition - Part 2 скачать в хорошем качестве

Glacial Lake Great Falls - Highwood Mountains Expedition - Part 2

After visiting the 50 million year old Highwood Mountains Volcanic Center near Great Falls, Montana, we visited some associated peripheral intrusive features, particularly laccoliths that invaded, altered, and split the older 85 myo Cretaceous Eagle Sandstone. It's hard to imagine our benign beige near shore marine Eagle Rims in Billings split by once 2500 degree F magma, leaving sedimentary layers sandwiched between hardened black layers! We also viewed the results of torrential floods from the retreat of glaciers 15,000 years ago. Despite age differences between the Eagle Sandstone (85 my), volcanism (50 my), and glacial outwash (15 ty), they are all related. The IPA Tour took us into the Highwood Mountains, up and into the Shonkin Sag, to the Square Butte vicinity to visit the Shonkin Laccolith, to Fort Benton, then back south across the Mighty Montana River (the Missouri).