Integrative Natural History of Minnesota's North Shore, Part 15: The Basalt Bloometh

Integrative Natural History of Minnesota's North Shore, Part 15: The Basalt Bloometh | Duluth

Taken at the same glacially abraded North Shore Volcanic Group basalt outcrop discussed in Parts 9-14 of this series. So we're at the southern end of Duluth's Kitchi Gammi Park, and just north of the mouth of the Lester River, along the Lake Superior coast.

I entitled Part 14 "My Final Foray in Abrasion Education," and to make good on that pledge I will not point out the set of parallel glacial striations just below the community of plants growing in a nook of the rock. Nor will I mention that striations are more fully described in Part 11.

The plants themselves, so prolifically in bloom at the Summer Solstice, belong to one of my favorite Great-Lakes-littoral species, Three-Toothed Cinquefoil, Sibbaldia tridentata. But if you're a botany buff of advanced age, you may know this taxon by its earlier generic epithets, Potentilla and Sibbaldiopsis. What hasn't changed is its placement in the Rose Family (Rosaceae).

I've seen this cheerful and remarkably hardy herbaceous plant grow in the most soil-challenged and wind-blasted places. And it's especially at home in cavities in this particular streamlined hunk of stone.

When the basalt that now surrounds this little ecosystem solidified from mafic lava about 1.1 Ga ago, a vast, horseshoe-shaped swath of Laurentia—ancestral North America—was cracking open during a time of crustal stretching. This feature, the Midcontinent Rift, produced a huge volume of basalt underplated by gabbro and anorthosite.

That timeframe, incidentally, was the final chapter of the Mesoproterozoic. As far as we know, the Plant Kingdom had not yet evolved, though fossil evidence suggests that its forebears, the Chlorophyta (green algae). first appeared during this era.

So when it first hardened on the Earth's surface, the North Shore Volcanics basalt was not adorned, as it is here, with bright-white flowers framed in glossy green foliage. At most, it might have had some green algal film growing in wet crevices.

To see the other photos and descriptions of this series, visit
my Integrative Natural History of Minnesota's North Shore album.

Taken in: United States / Minnesota / Duluth / Lester Park (show map)

Taken on: June 20, 2008

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Sets appears in: • Integrative Natural History of Minnesota's North Shore • MCR: Homage to the Midcontinent Rift more » • Natural History: Minnesota • Phytophilia • Rock Forms, Rock Formations • Structural Geology « less

Groups appears in: • Botany • Rocks and Geology more » • Geology Rockers • Wildflower Field Guide, North America • Midwest • Wildflowers • GeoTagging Flickr • Geotagged • Rocks • Geology • Minnesota Wildflowers • Rocks and Stones • Minnesota Parks • Geologists • USA - UNITED STATES OF AMERICA • nature and landscape photography • North American Nature & Wildlife Photography • Geology for all • Geology/EarthScience • Plant photography • Structural Geology • Natural Minnesota • Minnesota North Photography • American Photography • Rocks-Fossils-Minerals • Strictly Wildflowers • Nature Photography // • stones n rocks • I Love Rocks! • Midwest Nature • Natural Midwest *Please invite friends* • Geotagged: Minnesota • Geology Flickrs • USA Landscape Photography • Nature Album • Photography with a Story • Geology / Geologie • Nature and all that is beautiful • The Very Great Outdoors • US Wildflowers • We love Nature and Geology « less

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