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Far below the clifftop, the lake beckons between the birches as I set out on the short trail to Shovel Point one early June morning. The point rises inland to one hundred and fifty feet before dipping its cliffs over a quarter mile into the lake. Northern white cedars tether their roots to cracks high in its fluted walls while remnant white pines tower over the rock above. For years after I first moved to Minnesota, the trail to the point steadied my steps against a wanderlust that made me reluctant to settle. I rarely met a soul during my treks and nurtured illusions of harboring a private haven at the point’s far tip. Today, finding solitude on the shore in summer can be a challenge. Yet for each step I take, a sturdy bulwark of rock still firms up the foundations of the earth under me.

From the trailhead, I amble gently downslope through the forest and quickly reach a spur trail that descends a steep hillside to the lake. A small cove is bounded to the south by a long, low-lying forested point and to the north by a taller, shorter point. After making my way through the forest of the longer point, I arrive atop a tumble of rocky blocks and slabs at the edge of the open water and take in an unmatched view of the coast. To the north, Shovel Point dips steadily lakeward while to the south I can see the mouth of the Baptism River and the stately mass of a second, taller headland called Palisade Head. Together the two headlands bookend a distinct stretch of the central Minnesota shore. 

“Rhyolite: A Tettegouche Speciality” had read the caption on an interpretive sign that used to stand along the trail to Shovel Point. A few summers earlier I had attended a workshop on the geology of the central Minnesota shore with University of Minnesota emeritus professor Jim Miller. As our group stood at the mouth of the Baptism River, Miller held his cap against the wind and explained that rhyolite originated during a slowdown in volcanic activity from the Midcontinent Rift, when basaltic magma temporarily stopped erupting through the earth’s crust and instead pooled at its base.1 The hot pooling magma partially melted the surrounding older crust, creating a new kind of magma that when volcanic activity later resumed rose toward the surface and erupted through earlier basalt flows. Rhyolite accounts for a far smaller percent of rift rocks than does basalt. Unlike the thin flows of the latter, the rhyolite of Shovel Point and Palisade Head exploded in a steamy mix of shattered lava and ash that formed a slow-moving mass on the ground.2 Together the two headlands bookend a distinct stretch of the Minnesota shore, remnants of a colossal river of molten rhyolitic rock that reached at least fourteen miles long and over three hundred feet thick.3 

Long irregular flutes wrinkle the cliffs of both headlands, marking columns left by vertical cracks that sliced down through the cooling lava and created a pattern of columnar joints in the rock. Yet compared to basalt, the stickier rhyolite developed fewer joints as it cooled. It also developed fewer cavities from gas bubbles that rose up from its hotter interior to marble its upper layers, and it contained more of the hard mineral quartz. As a result it became a stronger rock, better able to withstand the grinding force of the glaciers that began advancing and retreating across the region around two million years ago.4 

The most recent major glacial advance began some eighty thousand years ago when a mile-thick sheet of ice spread south from Hudson Bay. Water that melted on the glacier’s underside from the friction created by the ice’s movement across the bedrock seeped into cavities and cracks in the lava flows and pried the rock apart as it repeatedly froze and thawed. While the basalt on the Tettegouche coast has mostly eroded away to form a tight ribbon of coves and points, the rhyolite survives as headlands and walls. Yet freezing and thawing waters seeped into the rhyolite’s cracks during the Ice Age. One chunk of rock after another was torn loose and carted away by the churning mass of ice. The waves of glacial lakes later continued to eat away at the cliffs, as do storm waves and frost action today. Slowly the two headlands retreat landward, shedding broken columns onto the lake bottom. 

 

The two headlands command the shore from the tip of the slender point on which I stand. Yet like many imposing landforms, they create bare pinpricks on a map of the lake’s total coastline. I eventually turn my back to the shore and gaze out at the water across the jumble of large blocks at the tip of the point. Against the scale of my human form, even the low point seems to extend a sturdy arm into the lake.

 

After making my way back through the woods, I wander onto the pebble beach that drifts up toward the hillside from the cove. The stubby point that bounds the cove to the north used to end in a wave-sculpted arch, but a decade and a half ago the arch collapsed in a storm, leaving behind a freestanding pillar of rock. A few years later the waves of another storm swept the pillar too into the lake, offering far more dramatic evidence of natural change than I’m used to seeing in the places I visit on the shore.

 

On the beach I see pebbles of both rhyolite and basalt, the latter tending toward paler reddish and lavender shades of brown and the latter darker shades of brown or gray and black. I lose myself easily to the pebbles, moving slowly forward with my eyes to the ground and my hand reaching for the next stone. On ledges and headlands, I mainly know different types of rock from the appearance of their weathered surfaces. Except for where frequently washed by waves or scoured by ice, the rock’s finer details remain obscured by lichen or a thin coat of blackish stain made of bacteria and other microorganisms. The clean pebbles, in contrast, offer microcosms of the hidden interior of the shore’s rocks. I pick up one pebble after another, turn it over, and then either drop it back onto the beach or place it in my pocket, the water and points little more than a blur at the periphery of my vision. 

 

Like other stones on Superior’s Minnesota beaches, those in the cove were left behind by the ice sheet, which along its margins spawned a writhing frozen tongue called the Superior lobe. As the lobe followed the lowlands of the rift basin, it ground through layer upon layer of bedrock and carved out the contours of headlands, coves, and points on the shore.5 Large chunks of rock carried in the churning mass of ice and debris were broken into progressively smaller and smoother pieces and then dropped in vast heaps of stone and sediment when the lobe melted back. Most sediments ended up further inland and to the south, but some sat within the reach of turbulent meltwater rivers that washed them into the Superior basin. Once in the basin, they were tumbled by lake waves and sometimes swept ashore to continue perfecting their forms by rolling back and forth across beaches.

The smoother a stone is, the further it has been carried by glacial ice or abraded by knocking against other stones in meltwater rivers and waves. While many pebbles on the beach in the cove have slightly angular, rougher shapes, some form perfectly polished flats or ovals. Either way, over time waves and weathering will reshape each stone in my hand as surely as they will the two headlands and the point with the former arch. So much that I take for stable and enduring on the shore is continually eroding and breaking down, more often than not quietly disappearing without my notice. Some day in the distant future, long after my time, the stones in my pocket too will wear down to mere grains, light enough to easily wash back into the lake.

While some basaltic pebbles on the beach have solid surfaces, others are dotted with amygdules or mineral-filled cavities. Rose, mustard-yellow, and white amygdules cover one umber-brown pebble that I pick up while a smaller nugget-sized gray pebble instead has thin oval bluish cavities with pale yellow margins. The amygdules were created by warm ground waters that percolated through the cooling lava and gradually dissolved elements in the basalt and created new minerals such as calcite, chlorite, and epidote, which were deposited in the cavities left by gas bubbles in the flows’ upper layers.6 Once the fluids evaporated, only the minerals remained, a Morse code of colorful dots. The occasional rhyolite contains tiny cavities lined with sparkling crystals of quartz.

I finally dig the pebbles from my pocket and hold them in my open palm. As I reflect on their long, turbulent journey through crushing ice, raging meltwaters, and battering waves, their forms stir a tenderness that makes me reluctant to release them back into the jumble of other stones on the beach. I walk to the edge of the beach and instead drop the pebbles into the water one by one and watch them settle on the bottom in a saturated blend of painterly hues. No matter how many times I’ve seen it before, the change in appearance from dry to wet rock always surprises me. Quicker than I can blink, each stone grows vibrant and glossy and reveals a fullness of character it lacked when held dry in my hand.

 

The trail to Shovel Point continues gently downslope atop the hillside above the cove. Thimbleberries bask in the filtered light under birches and honeysuckles cover patches of open ground. Before long I approach the lakeside cliffs and after crossing a footbridge over a stream gully begin a steady uphill climb toward the southwestern base of the point. The forest darkens with spruce, fir, and cedar, but as I approach the hillside’s sunnier top occasionally lightens with birch and young aspen. Wild gingers spread across the earth, especially around the birches. The wild ginger’s Latin name, Asarum canadense, was among the first scientific names I learned after I started wandering the Superior shore. In addition to flowing easily off the tongue, to this day it has a deep resonance. By now, the leaves on most trailside plants have grown to two to four inches long. Though some still angle upward, those that get plenty of light have started to fan out and form a loose carpet on the ground, a sure sign that the transition to summer is well underway in the forest.

For years after began visiting Tettegouche, the bare earth that alternated with simple, narrow steps on the trail up the hillside turned muddy with snowmelt and rain in spring. Yet as the construction of new condominiums and resorts proceeded apace on the shore and larger crowds flocked to state parks, the trail acquired a continuous string of walkways and steps that keep my soles off the ground and the park’s formerly homey visitor center was replaced by a sprawling structure with a large parking lot that fills easily in summer. Eventually the steep, weathered staircase that had made the final climb onto the headland was replaced by a more gradual and substantial set of steps. Though safer and easier to use, the new steps don’t evoke nearly the same feeling of adventure as had their rickety old counterparts. I climb them now, mourning the loss that changes to the trail and the growing popularity of the shore have brought to my sense of wandering alone in a wild land. 

Yet the top of Shovel Point preserves a remnant of the pine stands common on the shore before large-scale logging operations denuded the region of its forests. Once the gleaming waters come into view, I stop and breathe deep into air fragrant with sun-warmed bark and needles. White pines run long roots across low mounds of rock and bearberry, while mayflowers and blueberries fringe the mossier ground around scattered spruces. Pines are well-adapted to thin, rocky soils and Shovel Point includes both white pine and lesser amounts of red pine. The massive headland has no equivalent in the landscape in which I found small havens around the city of Gothenburg as a teen. Yet at its top, it too is a place of softly mounded, pine-studded rock where needles fill in grooves and breezes carry the rush of wind-swept branches and waters.

 

The surface of the rhyolite is mostly bare and nubby, with a dark lavender and rose tint partly obscured by lichen. I wander toward a few emerging harebells and three-toothed cinquefoils that hug gravelly crevices near the outer rim and try to gingerly peer over the edge, but remain too far away to see the cliffs below. A short distance to the south, however, the rim slopes lightly eastward and a cedar provides just the support I need. While steadying myself against the trunk, I spy a peregrine falcon zipping toward the cliffs, its long wings arcing back as it dips behind a protrusion in the rock. Peregrines had disappeared from Minnesota by the mid-1960s, their numbers decimated by egg collecting, sports shooting, and especially the widespread agricultural use of DDT.7 The banning of DDT in the early 1970s and reintroduction efforts beginning in the 1980s eventually returned the birds to lakeside cliffs, including at both Palisade Head and Shovel Point. Not far from where I stand, an orange sign marks an exclosure area set up to protect a nest site in the cliffs below.

From the rim, I can see a few cedars rising up the cliffs that reach toward the mainland. The trees don’t have particularly thick trunks and are smaller and tighter in form than their relations on the mainland hillside, but some have still grown to a seemingly impressive size for their precarious location. Also clinging to the cliff face are a few shrubby-looking birch saplings that, except for in the odd larger cleft, will probably eventually outgrow their meager perches and tumble into the lake. Yet for now, they too make do with bare nooks in the rock.

The view from the headland’s rim is striking. Set under a pristine sky with a few high clouds casting wandering shadows over inland hillsides and ridges, the coast to my south winds around one small point of craggy gray rock after another until it passes the cove with the pebble beach and reaches a salmon-tinted wall that extends toward the Baptism River’s mouth. The tight points below me mark the remains of the harder interiors of basalt flows while the recesses that separate them indicate places where the more cavity-riddled upper layers of the flow have eroded away.8 To the south of the river, meanwhile, the land rises to a forested bluff that marks the elevated shoreline of a former glacial lake in the Superior basin. The bluff has yielded archeologists over 280 stone flakes used as tools by Indigenous peoples before the arrival of Europeans in the region.9

At over 9,300 acres, Tettegouche is the largest state park on the Minnesota shore and from where I stand it’s possible to take in the formative history of a vast swath of both hinterland and coast. Another former interpretive sign by an overlook on the rim had explained that the rhyolite and basalt that dominate the coast cede inland ridges, hillsides, and peaks to three additional Midcontinent Rift rocks: diabase, gabbro, and anorthosite. Instead of erupting onto the earth, these other rocks cooled underground, diabase fairly close to the surface and gabbro and anorthosite at greater depths. Slower cooling underground created stronger rocks by giving mineral crystals time to grow in size and producing fewer fractures. Like rhyolite, these rocks therefore proved more resistant to erosion than basalt. Today, they create the high ground of the park’s interior while the basalt has mostly eroded away to leave behind valleys. Ultimately, however, they too were buried by more basalt, as well as by sandstones that filled in the rift basin after the lava flows ended, only to eventually be unearthed by the glaciers. 

I lean against the cedar trying to imagine the land both birthing itself and wearing down: tongue upon tongue of basalt gushing up from the rift, towering walls of rhyolite snaking across the earth, giant blocks of lightweight anorthosite riding waves of diabase up from the depths, and eons later immense plateaus of bedrock calving columns into infinite seas of grinding ice. When I finally turn from the view and look around the top of the headland, the rhyolite’s rose-tinted mounds seem both light and dependable, belying the violent history of the land. I know only snippets of the complicated geology of the shore, but the more I learn of its twists and turns the more this place offers me the grounding I seek.

 

From the cliffs, the headland slopes gently northward and a gravelly path leads downhill through the forest. Silvery needles sway on the upper branches of the pines, bunchberries and starflowers fleck the ground, and fir saplings stipple mosses in the shade. In clearings with roaming beds of sunshine, lacy pillows of reindeer lichen and blueberries with occasional white bells spread across patches of bedrock. I stop before a billowing mat of pale gray pillows accented by lustrously weathered twigs and cones and a few mayflowers and sprigs of bearberry with pink urns. Reindeer lichen are common on thin-soiled bedrock at northern latitudes, where the same gray species Cladonia rangiferina often mingles with one or two other species to cover the ground under sparse stands of pine and spruce. Though they can live for decades, their hollow, whorled branches grow slowly and the pillows never reach more than a few inches tall.11

 

Over the years, the reindeer lichen in clearings along the trail have joined needle-strewn soils in spreading out to all but conceal formerly visible areas of bedrock. The change occurred in the small incremental ways one doesn’t easily notice, a quarter teaspoon of soil filling in here, a lichen stem reaching out there, until the clearings no longer held the same patchy mix of bare bedrock and tentative growth that reminded me of outcrops I frequented in Sweden. Clear in hindsight but hard to discern at the time, the change in the clearings resembled the change in my relationship to the shore over the years. 

For over a decade after I began visiting the lake, I roamed widely across outcrops, river trails, and forested ridges, eager to see what the next ledge or bend would bring. The sight of reindeer lichen in the forest or harebells on an outcrop evoked occasional memories of Sweden, but rarely more. Yet eventually, in the midst of a series of life transitions, I began to long for the places I had left behind in Sweden and by then hadn’t seen in two decades. I revisited the cottage and returned a handful of times over the next several years. Whether I walked the shore or the outcrops of old havens around the city, each place stirred a depth of grounding that my longing from the United States had only hinted at. When I eventually returned to Lake Superior, I stopped roaming widely and instead began to linger and home in, year after year revisiting the same places and seeking out nooks and crannies I hadn’t given a passing glance before. Without any intentional effort on my part, the belonging I had regained on one shore rooted me down more fully on the other.

Now, as I continue downhill along the trail, a cool breeze begins to drift inland and cedar, birch, and fir become more common in the forest. Soon I glimpse the water between the trees and step onto a sloping rim of uneven rock high above the lake. The rim lies fully exposed to winter winds and its trees have a scraggy, stunted appearance. Dwarf spruce, fir, and birch grow in tight clusters, steadied on the thin-soiled rock by compact forms that offer shelter for wild gingers, bearberries, and other low-growing plants. Several spiny spruces near the gravelly edge of the rim consist of little more than a pole-like trunk with a few short, stiff branches. Even on a fairly calm day like this, the rim’s unnerving degree of exposure ushers me quickly along the edge of the forest toward the more gently dipping slope at the headland’s northeastern tip.

 

On the low-lying ledges common to the Minnesota shore, the transition between forest and bare rock is often abrupt. Storm waves wash inland and, scrubbing soils and plants from dips and crevices, and surging ice floes shear off plants, confining vegetation to widely scattered places of shelter.12 In contrast, the far slope of Shovel Point rises above the lake by at least several dozen feet and includes abundant mounds, basins, and fissures that offer protection for shrubs and flowers as well as a steep lower wall along the water. Along the forest that bounds its top, bearberries, serviceberries, and shrubs of honeysuckle and ninebark dapple a strip of grasses with fallen trunks and branches. Mosses and three-toothed cinquefoils hug patches of bare bedrock while reindeer lichen and mayflowers favor the near-edge of the woods. 

 

Below, the slope descends toward a broad craggy basin across grassy dips with mayflowers, pussy toes, and wild roses, as well as clusters of common juniper, blueberry, and other shrubs. Though the central basin is barer, three-toothed cinquefoils still wind along crevices, grasses fill in dips, and gooseberries, alders, and saplings of spruce, mountain ash, and small, shrublike birches shelter in hollows and behind short walls. Shrubby cinquefoils appear as one to two-foot shrubs as well as short sprigs in crevices, their leaflets, flower buds, and young red branches protected by silvery hairs. The vegetation is low-growing and sparing, yet a few shrubby cinquefoils and birches flaunt the wind atop mounds of rock. Beyond the low walls and humps that mark the far edge of the basin, the rock drops steeply into the lake. Little grows on the sheer rock, but the occasional sapling or shrub rises from a fissure there too.

 

I prefer the slope in the fickle warmth of early summer, before the grasses grow tall and the shrubs thicken with leaves, while the surface of the rock still lies awash in the colors of bare rhyolite and lichen. The rock mostly shifts between pale orange, burgundy-brown, and salmon-red, but except for in areas that channel runoff a dense skin of lichen gives it an overall grayish or yellowish-green cast. Dropping my pack, I pull out a guidebook entitled Lichen of the North Woods by Joe Walewski and read that northeastern Minnesota supports an unusually diverse lichen community.13 Lichen, Walewski had explained during a workshop I had attended, thrive on the region’s cool, moist climate, clean air, and varied mix of rocks, trees, and soils on which to grow.14 I bend low over one rosette after another, peer through my hand lens, and turn the pages to photographs of pale gray cinder lichen, yellow map lichen, elegant suburst lichen, and more. Disks of dusky brown rock tripe favor a few walls higher up on the slope. While some disks resemble coin-sized buttons, others have amassed into a light, wavy shag.

Lichens attach to the surface with rootlike filaments or hyphae that penetrate slightly into the rock. Their main bodies also expand and contract and freeze and thaw depending on moisture conditions and weather and often release weak acids.15 Over time, the freezing and thawing and erosive effects of the acids loosen mineral grains and etch the rock with fine cracks that capture runoff and nutrient-rich particles. Seeds may germinate in fragments of soil that gather around the lichens and plant roots needle their way into fine cracks.16 The surface of the slope undergoes constant slow-motion change. As I carefully wander around, I see diminutive three-toothed and shrubby cinquefoils, heads of sphagnum moss, and wisps of grass filling in mossy pits between gravels and areas of chipping rock. One three-toothed cinquefoil has only a quarter-inch red stem and a lone pair of minuscule burgundy-fringed leaflets. Until I began to notice these tiny plantlets a few years ago, I had never wondered how the generous patches of greenery that carpet the slope today may once have gotten their start. 

The vegetation on the slope is partially protected by the rising height of the rock, but storm waves still send frigid spray high into the air and barreling winds snap trunks and branches. Though a few spruces that grow in deeper dips or higher up on the rock reach well over my head, most stand no more than five feet or so. One tree has broken off at four feet and angles the remaining eight feet of its trunk toward the ground. Another has snapped at three feet. I wander toward a large cluster of spruces that sidles up to the mounded rock near an elaborate observation structure with long tiers of wooden steps along the slope’s northern end. A stocky trunk that has snapped slightly below the height of my chest has grown a whorl of branches from around its wound and shot a leader skyward to replace its former top. 

Over a dozen years ago, I arrived early one summer to find the tree missing its top and wondered if it would survive. According to my old notes, the small spruce cluster back then had sheltered a tight mat of wild gingers and lone blueberry shrub. Today, a large, spreading cluster of trees moves downslope with the dipping rock, a dense carpet of juniper, blueberry, mayflower, and bearberry rippling out from under its draping lower boughs and dead branches. I peer down at the greenery and even spot a few trailing twinflowers, dainty ground-hugging plants more common on the shade-dappled forest floor. 

 

The slope at the far end of Shovel Point supports an impressive range of growing environments. Yet most of its vegetation isn’t nearly as sheltered as that around the large spruce cluster. Tender and fragile, even at the height of summer, the greenery appears generous only relative to the expectations I’ve formed on low-lying ledges dominated by bare rock. For years after moving to Minnesota, I returned to the slope from late spring until late fall to watch shrubs and flowers move from bud to bloom to seed. A simple weatherbeaten viewing platform stood at the slope’s top, but few people seemed to linger and I often had the place entirely to myself. These days, even when no other people are about, the prominent new viewing structure gives the place an unmistakable human imprint. Yet just as with my old havens, each time I set eyes on the rock, instinctive memories of past visits evoke the same reassurance.

I finally pick up my pack and begin to walk south across the slope to follow the trail back onto the mainland. Before reentering the forest, I stop to look down at a stubby brownish wall that reaches out from the lower rock and dips toward the lake. The wall’s lower face has worn into the shape of a rough, shallow bowl and with each gentle, incoming swell wraithlike wisps of water rise and fall a few inches up its sides. While watching the rising and falling wisps, I see to my surprise that a cushion of shrubby cinquefoil sprigs grows only a few feet from the water’s edge on the far back wall. The cushion looks to have survived several seasons and maybe in a few weeks time will bear elegant yellow flowers.

As the season progresses, the slope’s lichen-studded rhyolite will gradually become a mere backdrop for an evolving mesh of floral color and greenery. Whether I return early in the season or late, years of previous visits help me anticipate the changes I’ll see. Summer after summer, the slope retains the contours of a dependable place, enveloping me in a palette of intimate yet ever varied forms as a massive anchor of rock descends hundreds of feet into the water below.

__________

1. Jim Miller, “What’s This Rock Too?: Unraveling the Geologic Story of Minnesota’s Central North Shore” (workshop, North House Folk School, Grand Marais, MN, August 17-19, 2018). I am indebted to Jim Miller for his clear explanations of geological processes and generosity in responding to questions during three workshops offered by North House on the geology of Lake Superior's Minnesota shore. 

2. John C. Green, Geology on Display: Geology and Scenery of Minnesota’s North Shore State Parks (St. Paul: Minnesota Department of Natural Resources, 1996), 39.

3. John C. Green, Terrence J. Boerboom, Susanne Th. Schmidt, and Thomas J. Fitz, “The North Shore Volcanic Group: Mesoproterozoic Plateau Volcanic Rocks of the Midcontinent Rift System in Northeastern Minnesota,” in Archean to Anthropocene: Field Guides to the Geology of the Mid-Continent of North America, edited by James D. Miller, George J. Hudak, Chad Wittkop, and Patrick I. McLaughlin, Geological Society of America Field Guide 24 (2011), 137.

4. Miller, “What’s This Rock Too?;” Jim Miller, "What’s This Rock Three?: Unraveling the Geologic Story of Minnesota’s Southern North Shore”(workshop, North House Folk School, Grand Marais, MN, August 25-27, 2023).

5. Miller, “What’s This Rock Too?”

6. Green, Geology on Display, 11-12.

7. Carol Henderson, “A Passion for Peregrines: How these falcons returned to the skies of Minnesota,” Minnesota Conservation Volunteer 83, no. 489 (2020): 32-43.

8. James D. Miller, Jr., Mark A. Jirsa, and Phillip Leversedge, Lake Superior - Born of Fire and Ice (Minnesota Geological Survey, 2000), retrieved from the University of Minnesota Digital Conservancy, https://hdl.handle.net/11299/93850.

9. Susan C. Mulholland, Seven L. Mulholland, Jennifer R. Hamilton, and Stacey Stark, Points and Pits: Archaeological Investigations in Minnesota’s Region 9: The Lake Superior Shore, Carlton, Cook, Lake, and St Louis Counties, Minnesota (Duluth: Duluth Archaeology Center, 2011), https://mn.gov/admin/assets/2011-Points-and-Pits_tcm36-187380.pdf, 76.

10. Miller, Jirsa, and Leversedge, Lake Superior.

11. Gregory T. Munger, Cladonia spp, in Fire Effects Information System, [Online]. (U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2008), https://www.fs.usda.gov /database/feis//lichens/claspp/all.html.

 

12.  Chel Anderson and Abdelheid Fischer, North Shore: A Natural History of the Minnesota Superior Coast (Minneapolis: University of Minnesota Press, 2015), 341; Minnesota Department of Natural Resources, “Lake Superior Rocky Shore Factsheet,”  Lakeshore System, Lake Superior Floristic Region, LKu43, https://files.dnr.state.mn.us/natural_resources/npc/lake_shore/lku43.pdf.

 

13. Joe Walewski, Lichen of the North Woods (Duluth: Kollath+Stensaas Publishing, 2007), 29.

 

14. Joe Waleswki, “Lichens: Pioneers of the North Woods” (workshop, North House Folk School, Grand Marais, MN, June 2, 2019).

 

15. Jia Chen, Hans-Peter Blume, and Lothar Beyer, “Weathering of rocks induced by lichen colonization — a review,” Catena 39 (2000): 121–146.

 

16. John R. Tester, Susan M. Galatwotsch, Rebecca A. Montgomery, and John J. Moriarty,  Minnesota’s Natural Heritage, 2nd ed. (Minneapolis: University of Minnesota Press, 2020), 123.

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