Two scientists weigh in on the importance of the interplay between animals and the geological ecosystems that form their habitats, and we share one spot where you can see it in action.
As the weather gets cooler, I’ve watched the squirrels, chipmunks, birds, and an occasional fox prepare for the upcoming winter. Not only can animals affect subsurface geology, but the geology shapes the landscapes, which in turn affects vegetation and wildlife distribution. This week, I had the pleasure of speaking with two geologists who have studied the connections between wildlife and geology, examining wildlife habitats in two different places and time periods. Let’s start by looking at some snippets from our conversations.
Sharon Lyon
Editor, GeoLifestyle
Burrowing into the Subsurface
Fossil Mammal Burrows, Jurassic, Morrison Formation, SE Utah. Courtesy of Derek Raisanen.
Derek Raisanen, lab manager and geology instructor at Howard Community College, conducted the research for his master’s on fossil mammal burrows in Southeast Utah.
Q: Derek, can you describe the results of your study of Jurassic burrows, specifically how the animals shaped their environment?
A: “Two new ichnospecies in the Morrison Formation were attributed to unknown mammalian tracemakers. Based on similarities to modern environments, we can assume these burrows and burrowers are moving nutrients into and out of the soil, facilitating drainage, aerating soil, and providing shelter for other organisms.”
Q: How did you know these were mammal burrows?
A: “Trace fossil identification was done through comparison to modern and fossil burrows.
The large size, overall complexity of the structures, and a more circular cross-section best fit a mammal.
Squamates (lizards and snakes) may excavate similar sized burrows, but they typically lack the mammalian complexity.
Mammal burrows may be excavated to accommodate two animals moving past each other, which tend towards a rounder shape.”
Q: How were their efforts recorded in the rock record?
A: “The burrows were preserved in a mudstone interpreted as a paleosol.
The exact mode of preservation appears to be the accumulation of carbonates inside the empty burrows. This is different from many other fossil burrows that are preserved suddenly when sediment comes in with a flood.
The slower method of infill would explain why there are no skeletal fossils of animals inside that were caught off guard.”
Q: I understand that the AAPG Foundation supported your research. How crucial was their support to your work?
A: “I am thankful for my AAPG grant, which funded all of my fieldwork over two seasons.”
Go deeper: Read the abstract of Raisanen’s work here.
Connecting Geology and Wildlife
Courtesy of Dr. Dale Leckie
Dr. Dale Leckie, geologist and author, has written a book titled Wildlife, Landscapes, and Geology: An Alberta and Saskatchewan Touring Guide.
Q: Dale, why have you branched out from geology to include wildlife?
A: “While exploring with my wife Marilyne and writing about the geology of western Canada, I became intrigued by the close relationship between wildlife and landscape. If you understand just a little bit of geology, you can understand where to find some of the best sights and fascinating creatures.”
Q: Can you give some examples?
A: “During the last ice age, western Canada lay buried under kilometers of ice, which scraped and molded the landscape, leaving it barren of all soils and life forms. Over the past 15,000 years, as the glaciers retreated, the land rebounded, creating deep river valleys like the North and South Saskatchewan, the Red Deer, Bow, and the Oldman.
These valleys now host forests of cottonwood and balsam poplars. The timing of the cottonwood's lifecycle is intricately linked to the rivers’ geological features, particularly their flooding patterns. The seeds of cottonwood trees will only germinate on freshly deposited sands. The trees then provide shade and habitat for countless birds, prairie rattlesnakes, and beavers.
Pronghorn antelope thrive on the semi-arid grasslands that cover the glacial deposits and old glacial lake beds. They evolved to outrun the now-extinct saber-tooth cat, American lion, and dire wolves, making them the fastest land animals in North America.
Burrowing owls, a rare sight today, inhabit the treeless prairie grasslands, relying on burrows dug by other animals, such as the Richardson’s ground squirrel, for shelter and food caches.
Sand dunes, remnants of the glaciers’ retreat, create unique habitats for creatures such as the Ord's kangaroo rat.
The rugged Canadian badlands, formed by weathering and erosion, provide a crucial habitat for reptiles such as the prairie rattlesnake and the greater short-horned lizard. These creatures rely on the warmth of south-facing slopes to survive the region's extreme temperatures.”
What’s next: Visit Leckie’s website to learn more about his best-selling books.
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One More Place to See Wildlife and Geology Interact
Rahayu Footage/ Shutterstock.com
Every spring and fall, thousands of golden eagles make their way to and from their Arctic summer breeding grounds to winter in the United States and northern Mexico.
The migratory route takes full advantage of wind patterns created by the thrust sheets of the Rocky Mountain Front Ranges.
Individual thrust sheets are oriented northwest and dip southwestwards into the prevailing wind. As a result, the westerly and southwesterly winds rise up the dip slopes of the thrust sheets, creating up-drafts above and in the lee of mountain ridges, which provide lift for soaring golden eagles.
When the winds are not overly strong on warm-to-hot days, eagles soar on thermals over the peaks.
During the pinnacle of fall migration, which just wrapped up in late October, it is possible to see hundreds of golden eagles migrating in a day from the right vantage points.
Many thanks to Derek Raisanen and Dr. Dale Leckie for helping us delve into how geology shapes the habitats that sustain life.
Understanding these connections can help us protect the delicate balance between wildlife and the ecosystems these animals call home.
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