Pre-modern Global History

Before European immigrants arrived to plow the fields, before traders and explorers mapped its contours, before indigenous people hunted buffalo across its plains, and before even Albertosaurus prowled the land, it was the stromatoporoids that reigned.

At around 2.8 billion years of age, the oldest surface rock of Alberta is young compared to the age of the Earth, which dates to about 4.5 billion years ago. Since that time, the molten fluids and solid rock that comprise the Earth have continued to migrate and shift, to move and change, tilting, buckling, crumpling, and rearranging the layers of rock that record the planet’s development. In the northeastern corner of the province, near Slave River, a small outcropping of the Canadian Shield reveals the

Precambrian development of Alberta that remains largely hidden by a much younger rock cover. During the 4 billion years of the Precambrian era, a lot happened, albeit very slowly; life originated, tectonic plates evolved and began their slow drift, eukaryotic cells emerged, and the atmosphere stabilized. The years passed, and land forms shifted and collided, joined and separated, rearranged themselves, banded into supercontinents and tore apart, until they sorted themselves into a configuration that might seem familiar today. That land that became Alberta was alternately subjected to flooding and drying, as seas advanced and receded. All the while, life evolved from microbes to complex cells to sponges and corals and shellfish.

By the Devonian period (353 to 410 million years ago), long before the Rocky Mountains rose to their majestic heights, the process that gave the province its natural gas and oil deposits was well underway. As the shallow, warm seas flooded in and out, they left behind the thick organic sludge of marine remains that would be pressure cooked into petroleum before passing into porous reservoir rock. By the period’s end, Devonian Alberta had become crisscrossed by reefs covering hundreds of square miles and sometimes growing as high as ten-storey buildings.

The primary reef builders were the indefatigable stromatoporoids, sponge-like creatures that were prolific reef builders for over 100 million years. They grew by secreting layers of calcareous sheets that formed hardened domes, sometimes exceeding 5 m (16 ft.) in diameter. It was the porous pockets and reservoirs of these reefs into which the petroleum migrated and where it was found millions of years later, earning the nickname “Alberta’s billion-dollar rock” for the fossilized remains of these industrious creatures.