HARD TRUTHS – The Telling Face of Rocks

This gray Keweenawan basalt, whose fifty-foot ramparts flank this stretch of the St. Croix River, is unfathomably old, dating from the Precambrian Eon, somewhere between 500 million and a billion years ago.

It is also the hardest basalt-type rock in America—so hard that boulders of it were used by NASA to test the drills employed on the moon probe.

And yet, these rocks are far from the static, silent objects they seem. There is movement here; those sinuous lines—visible only when the sun shines at just this angle—bring to the moment red-hot lava’s flow when life on earth consisted of little more than algae.

 There are distinctly human 
 utterances here.

VOICES OF TIME
These rocks speak volumes of a broad swath of history. Cracks and fissures recount epic battles between ice and stone, heat and cold, forces commanded by gravity. Lichens, some of their species nearly as old as the rocks themselves, bear testament to those ancient algae. For, in the face of otherwise untenable circumstances, only the subsumption of those algae by the lichen has enabled them to survive.

Near the cliff's base, the St. Croix’s natural scums and dissolved tannins have ranked water-level horizons on the rock face—a subtlety captured in just the last nanosecond of geologic time.

And, perhaps most compelling for their flesh-and-blood kinship with the likes of me, there are distinctly human utterances—portrayals of hands, a buffalo head and other symbols—likely made by Dakota or Ojibwe hunters nearly 1,000 years ago.
 

SHADES OF SHADE

 
A fascinating array of color and life forms inhabit this old windfall. Gnarly white bracket fungus oozes out of dark bark recesses...then doesn’t quite know what to do without a vertical surface on which to cantilever.

Emerald moss seeks out a bit more light on surfaces in brighter shade. And blue-green and gold lichen—a composite, symbiotic organism comprising both a fungus and moss’s more primitive cousin, an alga—likely took up residence here before either of its neighbors.

It is a study, too, of endurance. Fungi and mosses, surviving deep Minnesota winters, can live for years. Lichen, given a more durable substrate than this bark—which is being devoured by the fungus—can easily grow for centuries.

ART OF THE AGES – Lichen Painting on the St. Croix

The canvas: eons-old basalt. The medium: lichen, some of whose individual organisms may well have been here when the first European laid eyes on these cliffs. The artist: well…the Artist was here before there was a “here.”

It takes a moment of reflection to grasp the age of these rocks. They date from the Precambrian Eon, somewhere between 500 million and a billion years ago.

         The brushwork...looks wild and free 
         for work rendered so patiently.

This bluish-gray, Keweenawan altered basalt is the hardest basalt-type rock in America—so hard that boulders of it were used by NASA to test the drills employed on the moon probe. Since this type of basalt is found almost entirely on ocean floors, these terrestrial outcroppings in the Upper and Lower Dalles of the St. Croix River (which forms 169 miles of the border between Minnesota and Wisconsin), are considered quite rare, if not unique.

Some lichen species*, incredibly, are nearly as old as these rocks. First appearing on earth some 400 million years ago, they are here represented in at least five colors—including jet black. (Since there are hundreds of varieties documented along the St. Croix Valley, I won’t pretend to identify them.)

The brushwork—ranging from broad splashes, to wispy dry-brush, to seemingly random spots and drips—looks wild and free for work rendered so patiently. For that trick of time, for the composition of form and color and texture, the technique is breathtaking.

I am in awe.

* There are more than 10,000 species of lichen. They are composite, symbiotic organisms often comprising both a fungus and an alga. The former provides structure; the latter, sustenance, through photosynthesis. Most species grow less than a millimeter per year, and, given a durable substrate like this primordial basalt, can easily live for centuries.

LICHEN ON BIRCH

Lichen splashes cool, barely green, on silky birch paper.
Scorning guidelines, these lapping, liquid forms
belie the Artist's plodding brush work
in paint that well outlives the canvas.

(Flavoparmelia caperata is one of more than 10,000 species of lichen. Lichens are composite, symbiotic organisms often comprising both a fungus and an alga. The former provides structure; the latter, sustenance, through photosynthesis. Most species grow less than a millimeter per year, and, given a durable substrate, can easily live for centuries.)