The Alpena-Amberley Ridge

At this point in understanding ancient Great lakes history, we will focus on the Alpena-Amberly Ridge under the middle of Lake Huron.  If you don't know what this is, you'd better go back and read the previous post.

About 20 years ago, Dr. John O'Shea, an archeologist at the University of Michigan, was looking at this bathymetric map of Lake Huron, and spotted that shallower ridge running from southeast to northwest through the lake, here highlighted by black dashed lines.  It came to be known as the Alpena-Amberly Ridge, for the names of the nearest towns on each end, and it has been a focus of underwater archeology ever since.

There have been lots of advances in underwater exploration in recent years, usually from trying to find shipwrecks, so there are good tools for underwater archeology.  O'Shea took advantage of these and initially used side-scan sonar, finding evidence of rock piles that appeared human-made.  

Caribou are known to travel in regular routes, based on patterns in today's Arctic.  There indigenous hunters build small rock cairns creating 'drive lanes', making hunting more successful.  We once crossed one of these hunting spots, while paddling down the Burnside River in the Arctic.  A pile of antlers bore witness to the successful hunt.

Next they used a remotely operated vehicle which they named 'Jake', as well as actual divers to assess the appearance of this ridge.  The structures they found looked like drive lanes which could have been used to funnel the animals by creating bottlenecks where Indigenous hunters would be more successful.  They also found hunting blinds and broken arrowheads.

This description also immediately reminded me of Head-Smashed-In Buffalo Jump in southern Alberta, a site we visited on our first big trip west with our kids in 1986.  People visiting this site are of course entranced by the cliff the buffalo jumped over, and the kill site below.  Even archeologists focus on the kill site, because that's where you find ancient artifacts.  

But the real action took place above the cliff.  Here men of the tribe placed rock cairns built up with sticks and brush to create long drive lanes that the buffalo followed.  The real work was in finding a convenient herd and gradually working them toward these drive lanes.  (It was a lazy young brave who hid below the cliff rather than join the runners who had his head smashed in).

In this, another version of a bathymetric map of Lake Huron, you are looking at the Lake Stanley phase of the Great Lakes, approximately 7000 - 9000 years ago, when the Lake Huron basin was divided in two, and water levels were much lower than today.  The Alpena-Amberley Ridge stands out clearly.

The research led by underwater archeologist Dr. O'Shea has discovered an ancient caribou route across this dry ridge.  And further, it has documented stone structures built by indigenous hunters at narrow points of the ridge and what appear to be hunting blinds.

The research was not over yet though.  By gathering sediment and analyzing it they were able to reconstruct the ancient landscape, or what they labelled the paleo environment.  That's the next story.

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Caribou Hunting in the Great Lakes?

We attended a fascinating lecture at our regional museum last week, and it's got me interested in ancient Great Lakes history.  So I'm doing a little research of my own and I'm gonna share it with you over a few posts while we wait for the endless cold temperatures of early April to go up!

Leonore Keeshig, of the Saugeen Ojibway First Nation, spoke on indigenous legends that tell the story of retreating glaciers and a time when the annual caribou hunt was important, in a landscape that would be described as arctic, about 9000 years ago.  It was a landscape that would befie your belief today as you sail over the waters of Lake Huron and Georgian Bay.

So bear with me while I give you some background and then I'll try to explain the essence of her message.  Otherwise you can just skip this post and wait for the next one.  I hope you can get used to these maps.  They're kind of skewed, with north in the upper right corner but I'll explain them.

The upper left corner of this widely published diagram, shows the glaciation of the Great lakes, when lobes of the continental ice sheet extended down into Lake Michigan and Lake Huron.  Two lakes of meltwater sat in the south end of today's Lake Michigan and Lake Erie, labelled by scientists as Lake Chicago and Lake Maumee.  Drainage was to the southwest, through Saginaw Bay and Chicago to the Mississippi.

In the upper right diagram, the glacier has retreated north, allowing for a huge glacial lake to form, encompassing both today's Lake Michigan and Lake Huron, and the tip of Georgian Bay, labelled glacial Lake Algonquin.  It still drained to the southwest, as drainage north or east was blocked by the ice.  The shoreline of that lake can still be traced, considerably higher than the lakes today, including right here in Meaford.

The lower left diagram is the interesting one.  As the ice retreated north the lakes reached a point where they could drain to the northeast, out through today's French River and North Bay, reversing the drainage pattern completely.  This left the glacial lakes at a much lower level than today's lakes.  A smaller lake occupied Lake Michigan, known as Lake Chippewa, and similarly a smaller lake occupied Lake Huron, known as Lake Stanley.

It is at this stage, somewhere between 7000 and 9000 years ago, that we find tantalizing evidence of indigenous life on dry land that is today submerged.

Let me first finish describing the diagram above.  In the lower right corner we have a map showing approximately today's Great Lakes.  The water level was a little higher, so the Lake Huron/Georgian Bay/Lake Michigan basin was inter-linked and known as Lake Nipissing; Lake Stanley has disappeared, but there is still drainage to the northeast, through North Bay.  We can find clear evidence of this old shoreline right here in Meaford; indeed, it's just two blocks from my house.

Let's take a closer look at that Lake Stanley and the lowest water levels of the Great lakes basin.

I had always assumed that the glacial lake levels were much higher than today's lake levels, and they gradually fell, from glacial Lake Algonquin to Lake Nipissing to today's lakes.  But it's not actually that simple.  Glacial lake levels actually fell to a very low level, as in Lake Stanley, and then rose again to the Lake Nipissing level, and then fell again to today's lake levels.  So we have a gigantic up and down pattern going on.

When drainage shifted to the northeast, the lowest levels of the lakes were reached, with rivers connecting Lake Chippewa, Lake Stanley, Georgian Bay and a small corner of what became Lake Superior.  The green areas here were dry land, extending the shoreline far out from today's pattern. 

Take a look at how the Lake Stanley basin was divided in two.  Turns out that band of green running through the middle of the lake was dry land too, an underwater ridge known today as the Amberly to Alpena Ridge.  That's where we'll pick up next post; hope you're still with me!

The Snow Cycle Continues!

 Yes, it is still March today as I write this, and March never knows whether it's ready for spring or still has a bit of winter left to visit.  And so we had yet another gentle snowfall overnight last week, continuing what seems like a never-ending cycle.

It was only a couple of inches, but it turned the world briefly white again.

Our crane/snowstick got to do its work for a change.

Remember those white Hellebore; they got another dose of cold therapy.

And the Daffodil shoots out front didn't even seem to notice!

But I'm happy to report that things are now back to normal, and the only bit of snow left is down in the lower left corner, in the shade of the house.

And the Hellebore survived again, raising their blooms to a rainy late March day.  The dangerous ice storm the forecast warned us of ominously hasn't materialized yet.  But we did lose power at an awkward stage as they were attempting to get me out of bed.