Delving into Dirt: From Stardust to Soil

July 9, 2014 | Posted in: Science

Dung beetles adding to the soil's fertility, from Fabre's Book of Insects, Mrs. Rodolph Stawell, 1921.

Dung beetles adding to the soil’s fertility, from Fabre’s Book of Insects, Mrs. Rodolph Stawell, 1921.

“The earth is not a mere fragment of dead history, stratum upon stratum like the leaves of a book, to be studied by geologists and antiquaries chiefly, but living poetry like the leaves of a tree, which precede flowers and fruit – not a fossil earth, but a living earth; compared with whose great central life all animal and vegetable life is merely parasitic.” Henry Thoreau, Walden


Dust, soil, earth, grime, silt, muck, mud, gunk, filth, grit. The words for dirt are many, and few carry a positive meaning. If something is dirty, it’s in need of cleaning. If you’re dishing the dirt, then someone’s dark secrets are being aired. If you’re having dirty thoughts, please, keep them to yourself. But dusty, dirty, mucky material creates structure that holds together the organic and inorganic, allowing life to flourish, and the legacy of dust takes us back billions of years to the formation of galaxies.

“Five billion years ago a shimmering cloud created by supernova explosions began its gravitational collapse into a thousand new star systems. Throughout this vast cloud, new centers of attraction appeared with an infant star, like a jewel shining at the heart of each center. One of these centers became our Sun with its eight planets– a solar system.” Swimme & Tucker, Journey of the Universe

Our infant sun was immersed in a sea of miniscule elements, disbursed by supernovas. These elements, floating aimlessly, slowly began to brush up against one another and cling together, over time forming tiny balls of dust, which grew to the size of boulders, then mountains. Over millions of years, from such humble beginnings, the eight planets in our solar system were formed. To this day, the universe is awash in stellar dust:

“There are countless megatons of unknown dirt out there. The ejecta, dejects, rejecta, and detritus of ruined stars, it floats around the universe until it enters a field of force… If a very large mass accumulates, it may catch atomic fire and become another sun. If smaller masses form, they may become planets of solid, liquid, and gas. If still smaller, they may become the cold hunks of moons, asteroids, or comets.” William Bryant Logan, Dirt

Baby stars glow pink in clouds of stellar dust and gas, in this infrared image taken by NASA in 2006.

Baby stars glow pink in clouds of dust and gas, in this infrared image from NASA taken in 2006.

Earth is unique among known planets, balancing the extremes of solid, liquid, and gas. While Mars is a frozen sphere and Jupiter is a seething ball of gas, Earth has encircling its core an ever-moving ocean of hot liquid magma, which forms, moves, and slowly devours the tectonic plates covering, like a thin crust, the surface of our planet. In Earth’s early years, the planet was in a state of constant chaos, moving free and fast between solid, liquid, and gaseous states:

“This was a time of wild, frenzied activity—volcanoes rising up from the bottom of the oceans and boiling with lava, huge waves churned up by the tidal force of the nearby Moon. The oceans were a deep brown color; the sky was a pinkish-orange from an atmosphere rich in hydrogen sulfide. As Earth continued to cool, the steam that rained down for millions of years eventually covered the surface of Earth with an ocean of water…. Asteroids would hit the earth and the ocean would turn to steam once more…. Dust from asteroid impacts as well as from volcanic explosions blocked out the Sun. Night covered the Earth for millennia, until massive torrents of rain brought the dust back to Earth and a new ocean formed. After millions of years, more stable conditions emerged for rock, water, and air. Earth became encircled by great tidal oceans and was held by a thin layer of atmosphere.” Swimme & Tucker

The primordial oceans of Earth were life’s incubator, and the first single-celled organisms began floating in this chemical soup some four billion years ago, flowing as the waters flowed. Two billion years passed and the ocean-womb nurtured life into more complex forms, cells developing nuclei. Dust particles were still plentiful, but land was absent of life and without life, the rocky surface was washed clean of all minerals and dust, nothing able to catch hold and accumulate for long. When life first came onto land, it created the very first structure of organic and inorganic substances that would sustain all further flourishing of terrestrial life: the soil.

“Life did not crawl out of the sea on to the land; it oozed from the sea into the land, the organic acids of its excretions joining with the carbonic acid of the rainfall to create the first soft mantle of soil on the Earth. Maybe two billion years ago, the cyanobacteria began to use the sunlight to make sugars, excreting oxygen… This was the world’s first bloom. Scientists often attach to these colonies of free-living organisms the unattractive moniker ‘algal mats.’ Dense symbiotic colonies of cyanobacteria, fungi, and molds formed crusts that held dissolved minerals in place, preventing them from washing into the sea. They probably had all the various beauty of the organic, the red, the yellow-green, the filamentous, and the ramified lichen that cling to rock surfaces today…” Logan

Lichen was an early landliving pioneer and a creator of soil the world over. Illustration from Venska Lafvarnas Färghistoria, Johan Westring c. 1805.

Lichen was an early land-living pioneer and continues to be a creator of soil in its wide ranging habitats around the world. Illustration from Venska Lafvarnas Färghistoria, Johan Westring, c. 1805.

There was no soil before life extended its habitation onto land, and its arrival altered the face of the Earth, giving living organisms a structured, yet permeable, world to take root in. So, soil is not simply the accumulation of tiny particles of rocks, the fine dust of ground down mountains. Nor does a soil’s existence last as long as mountains. A landscape’s soil is an ephemeral substance, created by the interactions of earth processes with the cycles of life and death.

“The seasons, with their heat and their cold, make the soil. The storms make the soil, with water, the most powerful substance on Earth. The winds make the soil, spreading dust across thousands of miles. The tides make the soil, stirring the river deltas and their fertile slimes. And above all, the trees and the plants, the dead and the digested, the eaters and the eaten, make the soil.” Logan

A soil has its own life cycle, and without a steady supply of fresh organic material and minerals its lifespan is greatly shortened. Human interest in soil mainly extends to how fertile it is, and thus how much plant life it can provide. My own father, when our family moved into our first house with a yard, quickly began administering to the soil in the hopes of bringing about our own little Eden. He was relatively successful, with the help of a great deal of horse manure, which he declared “brown gold!”

“The characteristics of a fertile soil are in the dynamics of combination. It must not be stiff, dry, or stringy. The Romans liked to speak of the best soils as fat, sweet, and open. To them, a good soil held on tightly and let go lightly. Air, water, and nutrients were all abundant in them, yet they were not held so tightly so to clog up and cease to move… What seems to be best is soil that contains four to five percent organic matter and that is well watered and aerated to promote the microbial life that constantly converts the organic matter into humus.” Logan

Illustration from Lathraea squamaria, Anton Joseph Kerner von Marilaun, 1913.

Illustration from Lathraea Squamaria, Anton Joseph Kerner von Marilaun, 1913.

The rise of the first large-scale human civilizations were made possible by the intentional planting of specially selected crops. Cultures living in regions able to support agriculture had all developed the practice on some level by about 4000 B.C. Yet our understanding of the soil that feeds our expansive populations has been, and continues to be, murky at best, leading to the misuse of what is truly a precious and exhaustible natural resource.

“More technology, greater planting rates, more intensive use, greater dependence on larger holdings, and fewer farmers are supposed to save the day. Instead, they hasten decline. The Romans found out about it when their immense slave-farmed estates were exploited beyond the soil’s tolerance, leading to massive erosion and declined fertility. Medieval Europeans became so desperate to feed their booming cities that they took the leaf mould from the forests to use as compost on the fields, improving the latter briefly at the cost of the destruction of the former.” Logan

That which we regard with wonder and gratitude, we treat with reverence. The dirt, the very foundation upon which we live and sustain our lives, is ripe for a renewed reputation. So, the next time you’re cleaning off dirt from your floor or your fingernails, remember the creative potential of cosmic dust, the appearance of the first soil, and the long evolutionary trip life has been on since, supported and nourished by the dirt under our feet.

The following books informed this post:
Dirt: The Ecstatic Skin of the Earth, William Bryant Logan
Journey of the Universe, Swimme & Tucker

Just one person out of 7 billion + on a journey to live a life that is vibrant, soul-fulfilling, useful to others, and consciously engaged with the ecological community that sustains all life, including mine and yours.