Mount Rose - Once an Island!

Ice Age geology formed our current North Shore landscape.

NPS Photo / GM Spoto

Quick Facts

Location:

Mount Rose Trail

Amenities

1 listed

Historical/Interpretive Information/Exhibits

Mount Rose – Once an Island!

About 12,000 years ago, melting glaciers formed temporary lakes. The biggest, Glacial Lake Duluth, submerged most of the Grand Portage. Its shoreline was 738 feet (225 m) above today’s Lake Superior.

The shoreline of Glacial Lake Beaver Bay was where you are standing, 243 feet (74 m) above Lake Superior.Mount Rose was an island and Mount Josephine was surrounded by water on three sides! If a lake lasted long enough for waves to work against the shoreline, there is evidence left behind – beaches and bluffs, sometimes high above the present lakeshore.

The gentle slope before the Great Hall is the beach of Lake Sault, which had a shoreline 8 feet (2.4 m) above Lake Superior.