10,000 to 12,000 years ago, nearly all of northern Indiana was covered by a 100 foot+ thick ice sheet. There is no need to discuss anything that happened north of the moraine, at current Fort Wayne, Indiana and along the north bank of the Wabash River all the way to Lafayette, Indiana.
During this time, there were two primary, though inferred, influences on the environment: the ice and the constant cold water flows from the glacier, both worked to control the ecology, weather and the micro-climate of the region.
Directly south and adjacent of the pushed up gravel and wall of ice, mega fauna thrived. We know this due to the numbers of Mastodon bones and whole skeletons found in Allen Co. Indiana. (Thus, the naming of the mascot of our local State University, IPFW.)
For a number of millennia, the glacier move progressively north exposing earth and depositing silts, sand and gravels. Plant colonization would have easily kept pace with the receding ice flows. Plant colonies would be selected by topography and hydrology as it is today.
Likewise, animals would have followed the landscape. Musk Oxen were in Indiana in 12,000 BC, just as they are now in the Artic, which in many ways mimics the ice face of the Paleo-glaciers (with the exception of the solar period, which will not be discussed here).
Returning to the protagonists introduced in “B P, W P 1,” the North American Beaver, Castor canadensis, would have been an early animal colonizer in front of the retreating glacier. Willow, Salix spp. and Cottonwood, Populus deltoides are aggressive, air sown seeders. Likewise, the wet, planed soils and topography would have been ideal for the two species to flourish. Couple this with the plants’ wide tolerance range and rapid growth rates. It is an easy projection to see groves of these two trees springing up within one or two years of the glaciers next “jerk” north.
Is this change a prime causation to the extinction of the mega fauna? The radical and rapid change induced by the retreating ice (another thread ignored . . . this time). It is possible the wooly’s didn’t eat Willow and Cottonwood! But, it is the primary food of the beaver.
If 21st century beaver behaviors mimic their ancient ancestors; exploration, mud dams and foraging for plants big and small, makes them a natural to follow the ice all the way to the Artic Circle.
So within 10-20 years of the “icewall’s” retreat, every lowland and drainage became beaver zones. The only variable of control was food (willow and cottonwood) and their reproductive capacity . . . and beavers are “rats”.
