By Amy Singer, PhD
It’s time for Field Notes, brought to you by the Montana Natural History Center.
The first oceans I explored as a child were those of eastern Montana. I spent nearly three decades of my life in ancient oceans before I ever got my feet wet in a modern living ocean. Working on my doctorate in paleontology, I cried the first time I saw a living bryozoan, a colony of tiny animals similar to coral, that I had only known from stone now alive in my hand, popping open their tiny operculum doors to feed. Much of Montana has been a seafloor for millions of years, notably twice during earth's history: during the Carboniferous, roughly 300 million years ago, and during the Cretaceous, when the Great Interior Seaway split North America from the Gulf to the Arctic starting about 100 million years ago.
I have always been perplexed as to why people say eastern Montana is ugly or boring, like, have you actually seen it? Its eons of life? Its oceans both watery and grassy? A landscape where you can walk on not only the most diverse remnant of North America’s savannah, but millions of years of oceans beneath your feet. Have you seen the Rimrocks of Billings, which were formed by sand dunes and a great river delta bordering the continental-scale Cretaceous seaway? From there you can look across the Yellowstone Valley to the fossil-rich lagoon that is the South Hills. Have you wandered the coral reefs and oyster shoals of the Pryor Mountains and found bits of the giant sea turtles that once hunted there? Near Shawmut you can dig clams bigger than large men where anglers now fish for trout where sharks once swam. Have you ever admired palm tree fronds from the Judith River Formation beneath the ponderosa pines along the Musselshell River? It was named by Lewis and Clark and favored by Indigenous peoples for the modern freshwater mussels in the mud, where once marine mussels, millions of years older, measured in feet rather than inches!
I've never fished Fort Peck, but I have hunted lobster in the surrounding hillsides in solid balls of limestone. Famous for its dinosaurs, the Hi-Line bears some of the largest ammonites I’ve ever seen. I have dug some of the richest fossil ecology out of the fish-bearing cliffs north of the Snowies, where Indigenous people painted some of the oldest pictographs in the Americas, and ranchers now run their cattle, grazing grasses enriched by ancient oceans. The Missouri River Breaks and Bighorn canyons stand as stony encyclopedias of the great oceans that rose and fell over our state. The Madison Limestone that extends from southern Canada to Nebraska and lies beneath most of Montana was built from tiny saltwater invertebrate animals 350 million years ago. Now it’s an important freshwater aquifer 2,000 feet thick in some places.
I grew up learning the language of oceans in the sandstones and limestones of eastern Montana. From atop the Pryors, I can see the tiny sparkles that are Lovell, Wyoming, and Red Lodge and Billings, Montana, sitting on what was likely an island more than 65 million years ago just beyond a narrow strip of land that is now the Bighorns. I can gaze across waves of grass that could easily be waves upon the Cretaceous and Mississippian oceans as far as the eye can see.
As I sit on the Carboniferous carbonates of the Snowy Mountains, I can imagine velociraptors chasing small theropod game along the beaches that will form the Mesozoic sandstones of the Bull Mountains, not dissimilar from coyotes or wolves chasing antelope today. Sitting in one ocean, looking to another, 200 million years apart. From these island mountain ranges in the great northern plains of eastern Montana that let me peek so deeply into the past, I love to look over eons of oceans and millions of species of fossil organisms. I breathe deeply of that big sky and those ancient oceans that now smell of sweetgrass and sage rather than sargassum. And I marvel at how life has thrived here time and time again for millions upon millions of years in oceans both wet and dry.
Today’s Field Note was written in the Field Notes Writing Workshop at the Montana Natural History Center. This is Amy Singer for Field Notes, brought to you by the Montana Natural History Center, providing natural history education for schools and the public throughout Montana. To find out about upcoming events and programs at the Center, call 406.327.0405, or visit our website at MontanaNaturalist.org.
