The Geology of Cook County: Oceans, Volcanoes, and Glaciers, Oh My!

Date: August 15, 2025

Time: 5:00 pm - 7:00 pm

Location: Grand Marais Public Library

Event Description

The Geology of Cook County – Geologist Al Trippel will present on the rocks of the North Shore for rock hounds of all ages.

In this presentation, Al Trippel will explain the geological and historical context to the rocks we find, whether washing up on the shores of Lake Superior or unearthing themselves on the Superior Hiking Trail. Cook County is home to a variety of rock types, some common and some extremely rare on earth. The presentation will show us where we sit in the regional “big picture” of the Canadian Shield “stable” craton.

The presentation will include a slide show, exemplary rocks, as well as digital and print resources about how and where to find agates and other fascinating rocks and minerals. A question and answer session and rock-identification segment will conclude the presentation. If bringing in rocks for identification, limit rock-ID questions to two rocks per person, for time will be limited.

This free program is for rock hounds of all ages.

Al Trippel lives in Grand Marais and grew up around rocks in the Midwest and Western US.  From a childhood hobby, to a high school job, to a career in mining—and now a passion during retirement (actually he calls it “refirement”)—rocks continue to awe and inspire him. Much of his lapidary and jewelry making utilizes rocks and minerals found along the way.

Additional Info

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The Geology of Cook County: Oceans, Volcanoes, and Glaciers, Oh My!

Location

sparkling wintry lake superior and ice sheets stacked on north shore

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