Natural Connections: Patterns In Sand

The lichens and mosses here are gripping on to sand grains eroded from the cliffs above the sea caves in the Apostle Islands National Lakeshore.

Natural Connections: Patterns In Sand

Sand scuffed under my boots as I hiked up and out of the river bottom. The desert stream we’d eaten lunch near was running high after winter rains near Sedona, AZ. As we climbed, the chill I’d felt while sitting dissipated, and I paused to take off a layer. Hiking in a tank top in January was quite a treat.

“Check it out!” I exclaimed, as the patterns on the steep bank next to the trail caught my eye while I stuffed my long sleeves in my pack. Pausing and looking down is often a recipe for spotting something fun, and this time was no different.

The soil on the bank was sculpted into miniature towers, buttes, spires, and hills. Some high points—standing an inch or two tall—were capped by a pebble. That hard surface would protect the sand below from the erosive force of raindrops, just like a layer of harder cap rock forms the top of a full-size butte.

Little flecks of dark brown lichen covered some of the petite hills, their odd shapes fitting together like puzzle pieces. In one patch, pale pink lichen flakes glowed in contrast. Truly minute bits of lichen coated the sand in a black film, and tiny tufts of green mosses stuck out of them like beard stubble.

“Cryptobiotic crust,” I’d learned to call this strange microcosm when I first worked in the desert of Southeast Utah after college.

Cryptobiotic crust is the community of tiny living things who glue together the surface of some soils. Cyanobacteria move in first. While often referred to as blue-green algae because of their ability to photosynthesize, they are actually ancient bacteria who played a part in creating the oxygen-rich atmosphere we enjoy today.

Although dormant when dry, the sheaths surrounding cyanobacteria cells swell and produce filaments as they absorb rainwater. Damp filaments weave among the soil particles and grab on. As the cyanobacteria dry out, the filaments secrete complex sugars which harden into glue.

Over many years and many cycles of wetting and drying, a fragile crust develops. It prevents the sand from blowing away in dust clouds or becoming shifting fields of dunes. “Crusts are the glue holding this place together,” claims my well-worn Naturalist’s Guide to Canyon Country.

But the desert isn’t the only place woven together with life.

This past October, on one of those last sunny days, I hiked the Lakeshore Trail in the Apostle Islands National Seashore. The path begins above Meyer’s Beach and winds northeast through the woods.

Over millions of years, water has carved the reddish sandstone bedrock into headlands and inlets, cliffs, and of course the sea caves. If you’re willing to hike up and down through steep ravines, along narrow boardwalks, and up several sets of stairs, the rewards are spectacular.

Lured by the lake’s cerulean blue and the craggy form of a tenacious red pine, I ventured out on a narrow headland with cliffs falling away on three sides and spectacular views of the sculpted rocks on the headland next door. The view commanded me to pause and take a long look. Before turning to leave, I closed my eyes and inhaled a deep breath of sun-warmed pine needles.

I’d laid my trekking poles near the base of the red pine tree to leave my hands free for my camera, and as I bent to pick them up, a new view—no less spectacular than the waves and cliffs—recaptured my attention. “Check it out!” I exclaimed.

Tiny forests of mosses poked up between pale sand grains. Carpets of bluish lichens protected little hills, and pixie cup lichens raised their chalices as if waiting for the right vintage of raindrop. Here, miles from the desert, was another community of cryptobiotic crust holding together sand as the stone falls apart. The sandstone on the South Shore is five times older and gets twice as much rain, but otherwise is not so different from some of the rocks of the Colorado Plateau.

Crouching in front of the little garden—protected from crushing footsteps by the twisted roots of that tenacious pine—my eyes roamed through the miniature landscape on an epic adventure. Climbing hills, seeking rest in the soft swales, discovering new life forms on every peak, I traveled while my feet stayed still.

Looking up from Lilliput, I saw the patterns of diversity and connection in that small patch repeat themselves in the forest, across the landscape, and throughout the world.

Author’s Note: Portions of this article were originally published in 2019.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Last Update: Feb 01, 2023 9:14 am CST

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