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Shape and angle of the impression

It is certainly hard to see in the photos, and believe me when I write that it was also hard to see in person. At some spots these tracks were invisible to see entirely, and some you had to look at the trail in just the right angles to see the faint snowed in trail. But we took the time as we wanted to fore track the Fisher, to follow them in the direction they were going in, rather than back track and go in the direction which they had been coming from.

When we first came up to the Fisher trail we quickly examined the faint impressions to look for the shape of the impressions. I wanted to see if there was a broader rounded edge and a narrower tapering edge of each track. The broader, more solid edge of the track would be where the toes are, and this edge tends to be deeper than the heel or back of the track, as I have noticed that most wild animals tend to be a bit more “toe heavy” and their feet sink in at the front a bit more. The heels however do not always register in the track as deeply and tend to taper in appearance and depth. So in the photograph above and the poorly drawn image on the right would both indicate that the Fisher’s DOT is towards the top of the screen.

Look for the toes

Even though we didn’t find any clear tracks on this particular trail, looking for impressions of the toes at the front of the track is very useful technique for discerning the DOT. Deep incisions into deep snow are often angled in such a way that we can’t see the track floor where the actual imprint sits. We can still use this track to determine the DOT by digging away a few layers of snow, or taking off our gloves and using our bare hands to feel the track. By doing this you can sometimes feel the number of toes, or the ridges between the toes like the cleave between toes 3 and 4 of a deer.

Behaviour like turns and stops + Look for the track pattern

As we carried on the Fisher trail we encountered a couple of times where the Fisher slowed down and investigated. We couldn’t tell what the Fisher was concerned with but we could tell that they slowed and turned. One way we could tell this was by looking at the track pattern left in the snow. In the photo above, the Fisher slowed to a walking gait as they made their way up from the bottom right of the image. Then their trail arced back towards the bottom left of the photo before quickly continuing on their trail in a loping gait towards the top of the image, leaving behind quicker 3×4 and 4×4 track patterns.
We can look at the track patterns and consider the movements of the animal by comparing with what we know about Mustelids (the Weasel family to which Fishers belong) and by thinking of ourselves. Weasels and humans tend to slow down when when investigating something. We will walk to look carefully, and only when we are ready to move on will we jump back into high gear and take off again. This change of gait, from a slow exploratory walk to a faster 3×4 loping gait used by Fishers to cover ground, can be seen as an additional tell of the DOT in the trail. So once we see the DOT we can recognize that the track patterns left behind indicate that the animal moving from the bottom of the image, across and arcing to the left, then up the image and out of the frame.

If we were to imagine the Fisher or ourselves coming from the opposite direction, from the top of the image down towards the bottom, we could see that the animal is moving quickly because of the track pattern indicating a faster gait. They then stop suddenly, without an apparent disturbance to the snow, leaving no slide from slipping, no thrown debris from the forward momentum. The trail would then have to be interpreted as the Fisher walking steadily backwards in an arcing trail until out of the frame on the lower right. While I have seen a Mink (Neogale vison) walking backwards to avoid being noticed, this behaviour is pretty rare and unlikely. Instead we have to assume the more likely storyline, while putting the pieces together in a logical way, noting the behaviour of the Fisher. If we do this we can see that their DOT was towards the top of the image.

Pointing with feet

Pointing with feet implies the times when an animal is looking in a specific direction, perhaps to see what is going on, or to listen, or perhaps even to browse on some nearby shrub. The animal will put out a front foot in the direction that they are looking. The track may be very lightly impressed in the snow. The track will appear out of baseline, out of the regular rhythm of the regular track pattern left behind, indicating that something happened here and it is worth checking out. This is also a moment to determine the DOT because the front foot, either left or right, will be facing forwards towards the DOT but perhaps slightly to the side.

I see this a lot with ungulates such as White-tailed Deer (Odocoileus virginanus) and Moose (Alces alces), but have also see this with Lynx (Lynx canadensis) and Coyotes (Canis latrans). I realized I didn’t get any photos of this behaviour, but it could be lumped with the heading above.

Debris

As mentioned above, another good way to determine DOT is to look for debris in the trail, especially snow kicked up at the front of a track. I was discussing this characteristic with a student this Winter who was quick to demonstrate that snow will be pushed out of a track to their rear, pushed behind them as they lift their foot as result of forward propulsion. They then replicated this by sticking their boot into the snow in a mock step and then intentionally dragging snow out behind them. My response was to point something out ahead of them, something too small to see from where they were standing. They had to walk over to the fictional point of interest, now distracted from the point they were trying to make. When they have walked over to take a look, distracted from the point they had just made, I got them to stop, turn around and look at their trail. Most of the snow had piled at the front of their tracks where they lifted their boots out of the snow. This was pretty convincing.

Now, snow or other substrates can be thrown back behind a track when an animal, including humans, are moving at a faster pace, pushing off of the ground with a forceful step, but I only remember seeing this when someone is starting to move in a run. When I think of it now, it makes me want to go out and try some experiments with a tracking class and see what we can figure out. Will more snow be thrown backwards as more force is being used to propel a body forward?

Recently, at a TCNA “tracker tuesday” call, there was a challenge proposed: on your next tracking outing, practice following the deer or the rabbits and see if you can find 10 plants which they fed on. For me in my area, the deer would be White-tailed Deer (Odocoileus virginianus) and the rabbits would be Eastern Cottontails (Sylvilagus floridanus). While I have been observing the Cottontails loosely at work with my students, for this tracking outing with the Earth Tracks Wildlife Tracking Apprenticeship, we focused on the White-tails.

Winter food finding in Southern Ontario is tough for all species. Not only is there a lot of snow on the ground, many of the common forbs which the Deer consume are long dead and the remaining and accessible plants are mostly tougher woodier species which tend to be harder on the teeth and harder to digest. In addition to these impediments White-tailed Deer prefer a mixed bag of food sources. They tend to seek out a variety of mixed forage. While occupying smaller “yards” or Winter territories the White-tails often have less diversity of choice. While their Spring, Summer, and Fall diets are of a more cosmopolitan variety, in Winter they are forced to live off less.

It’s important to consider not only what the deer are eating, but also how. Let’s remember the basics. White-tailed Deer bite off the ends of twigs with their incisors, the teeth at the very front of the mouth. We may think of our own incisors at the top and bottom in the front of our mouths, but when it comes to the Deer they only have incisors on the bottom mandibles. This is also true for a few other species as well, such as everyone else in the family Cervidae (including deer, Moose, Caribou, Reindeer), members of the families Giraffidae (Giraffes, etc), and the family Bovidae (Cows, goats, sheep, etc). All members of these families have no incisors in the cranium. Instead, when they bite those twig ends off they rip them off by grasping the twig end between their lower incisors and the hard palate above. Some other species, such as members of the Rodentia and Lagomorpha orders, cleanly slice twig ends off, but for these no-upper-incisor-having species, it’s often a ragged rough hewn rip. See if you can see this in the photos below.

In “Deer (The Wildlife Series, Book 3)” (Stackpole Books, 1995), Dietland Muller-Schwarze wrote that Deer, like other ungulates, have quite a lot of circumvallate papillae (one type of many bumpy structures on the tongue that gives it the rough texture). In Humans (Homo sapiens), we have between 8-12 of these large structures near the back of our tongue and each structure holds about 100 taste buds. These taste buds on the circumvallate papillae are especially sensitive to bitter tastes. Muller-Schwarze writes about how Deer will commonly spit out bitter forage when they come across it, but for me, this begs the question of how bitter is too bitter for a Deer? Some of the plants described above and below can be pretty bitter tasting to me but I am curious about the time of year when bitterness is most expressed in a plant? I think of bitter annuals in early Spring like some of the Mints (Lamiaceae) and Mustards (Brassicaceae), how often to the Deer munch on these? Perhaps we’ll need to keep an eye out in the Spring to find out.

Lucky for the Deer at Kinghurst, there is a variety of fine forage for them in the Winter. Here I will share some of the variety of plants which we observed feeding sign on, listed in the order in which we came across them. I would love to trail the deer in other areas in Southern Ontario and see what they forage on there. Next time..

1) Alternate-leaved Dogwood (Cornus alternifolia)

The Alternate-leaved Dogwood is also known as Green Osier and Pagoda Dogwood. I think Pergola would be a better name as a pagoda is multistoried and closed on the sides, while a pergola is single storied, and open, more closely resembling the growth form of this outlier in the Cornus genera. I write outlier because the Alternate-leaved Dogwood is just that, alternately leaved and branched, while the rest of the Cornus are opposite branched or whorled. White-tailed Deer tend to consume both the leaves and the twigs.
C. alternifolia is plentiful at Kinghurst. They tend to grow as an understory shrub in open woods, ravine slopes and hillsides, in forests with mature canopy species such as Sugar Maple, Eastern Hemlock (Tsuga canadensis), and Yellow Birch (Betula alleghaniensis). There are the places where the White-tail tend to hang out.

2) White Ash (Fraxinus americana)

Common species in the upland forested landscape which I tend to see coming up quickly in areas where other coniferous trees have come down, leaving a gap in the canopy. Most of the larger White Ash and Black Ash (Fraxinus nigra) we found were riddled with Emerald Ash Borer (Agrilus planipennis or EAB) sign and epicormic shoots, but the younger ones the deer were hitting, not so much. We did find one massive old White Ash with a Winter Porcupine (Erethizon dorsatum) den in the base, with the Porcupine huddled up inside. I did not see any sign of EAB on this big one and wonder if they are resistant somehow? If this individual tree is resistant somehow, I hope they are a pistilate or seed flower bearing individual (White Ash trees are either pollen flower bearers or seed flower bearers) and survive to spread viable seed with that same possible EAB resistance. We noticed lots of feeding sign adjacent to the den, but this was Porky sign with 45°ish cuts at the end rather than the ragged cuts the deer tended to leave behind.

3) Eastern White Cedar (Thuja occidentalis)

Eastern White Cedar is the one of the most important food plant in the Northern woods; one of the only green plants in the NorthEast which can sustain deer in the critical part of Winter. Aside from being an essential food source, White Cedar also provides good thermal cover in the Winter months similar to Eastern Hemlock (Tsuga canadensis). The White Cedar grow in tight groves helping keep the snow cover below shallower than surrounding open forests.

As White-tailed Deer move through White Cedar groves they tend to feed on all the green leaves from the lower branches within reach, often creating visible, generally uniform horizontal browse lines. These browse lines are a clear indicator of White-tailed Deer population in a given area.

4) Black Locust (Robinia pseudoacacia)

Black Locust is a tree that I have read described as a non-native invasive species which chokes out local tree populations. I have seen this native to the faraway distant (note the sarcasm) mountain tops of Pennsylvania to be an early colonizer of meadows and preventing erosion by stabilizing soil with an extensive root system. The bees love the beautiful and tasty flowers and it seems the White-tailed Deer appreciate the young shoots for Winter browse. The Black Locust was once planted for the valuable wood and also as a beautiful ornamental with their amazing dangling, pungent flowers. While the thorns may be irritating, they have developed on the tree to prevent too much herbivory by from the Deer while still giving something in the way of a good food. If only we could all learn good boundary making like this plant.

I noticed many of the individual Black Locust trees growing at Kinghurst were growing in open canopied clearings along the edge of the pine plantations, and this makes sense as they are intolerant of shade. I would imagine as more mature trees come down in that forest, more Black Locust will be coming up. They can do this quite easily, and they don’t need seeds. The Black Locust commonly spreads by sending up “ramets” or shoots from underground runners. If the Deer did consume a new shoot all the way to the soil, then the root would just send up another one.

5) White Pine (Pinus strobus)

For all it’s ubiquity, I don’t believe I have ever noticed White Pine being browsed by the Deer until this occurrence. I know this is a common occurrence detailed in the literature I have read, but I had not seen it before. I appreciate this assignment as I am now looking at this pretty common species in new light and noticing something that has likely been there forever, but is new to me. The White Pines I encounter also seem to be very large and in mature forests where the White-tails cannot reach the lowest branches but I am going to have to pay a lot more attention now just in case.

6) Common Blackberry (Rubus allegheniensis)

Similar to the Black Locust above, the Blackberry has a perennial root which sends up shoots. Instead of ramets, they are called canes which have a two year life span. Also similar to the Locust, Blackberry is intolerant of shade, I guess I am seeing a pattern. The Locust, and the Blackberry were both growing at the edge of the Pine plantation. This lets me know that the area is likely pretty sunny and that the Deer are moving through there.

White tailed Deer population thrive in edge spaces. The edges of a White Pine plantation, the edges of a field, the edges where suburban homes meet the green corridor protecting the creek. These are also prime places for the disturbance adapted plants such as Blackberry and the Locust and a host of other forbs. These help create a rich and varied diet for the Deer.

7) Red-osier Dogwood (Cornus sericea)

The Red-osier has a broad range, covering the boreal and temperate forest regions across the continent, so of course the White-tailed Deer, with a similarly broad range will encounter this shrub. Identified by the red bark on twigs and upper branches, a red which appears to grow redder when the Winter season starts to consider the shift to Spring. Often growing in wetter areas, good to look out for to know where the water might be in a snow covered landscape.
This shrub has taught me a lot over the years. So much so, that I purposely go check out the C. sericea when I am out tracking because it is very likely I will find sign of deer browse. I don’t know if it is the ubiquity of the plant or the blazing red which draw the deer in, but they appear to like this one a lot. I have seen some Red-osiers hit so hard they look as if a bonzai beginner just learned how to use their sheers and got snip happy, stunted and oddly growing, though without a clean cut. This is a good one to look out for on the land when wondering where the deer may be hanging out.

8) Black Cherry (Prunus serotina)

I associate many of the included species with medicinal action in the human body, and I wonder about these same actions with the Deer? I recognize we have different physiologies, but could they work similarly in an ungulate body as they do in a primate body? And if there is similar action medicinally, what about toxins? I have found White-tailed Deer browse on deadly poisonous Water Hemlock (Cicuta maculata) in the past yet did not find a dead Deer beside the plant. Same with Canada Yew (Taxus canadensis); feeding sign, but no dead animal. Do the Deer feed on the foliage of the Black Cherry or just the twigs? The leaves are full of cyanide and could be pretty harmful but perhaps the Deer have more suitable browse in the months when the Cherry leaves are present? I have also read that the twigs have cyanide present, but perhaps not as much as the leaves? Or maybe it just doesn’t bother the Deer at all and they’ll just eat what they want?

9) Sugar Maple (Acer saccharum)

Sugar Maple is a tree I could also get down with munching on. While a little bit bitter from the chlorophyll, the inner cambium still tastes pretty good. Yes, I have tried it. I have also eaten some buds on Sugar Maple in the past and I remember thinking they were palatable. Something I have also learned through the apprenticeship program is to identify Sugar Maples by looking at their the buds at the end of the branches, also called “terminal buds” (which happens to be the name of my nature gang). Sugar Maple terminal buds tend to narrow towards the tips and are more pointed and sharp feeling than, say, a Red Maple (Acer rubrum), which has rounder terminal buds. So the mnemonic “sugar sharp” can help us remember the Sugar Maples, and “red round” for the Red Maples.

10) Wild Grape (Vitis sp.)

A couple of weeks ago during an apprenticeship meet up at Dunby road, we had found feeding sign from White-tailed Deer on some feral Apples (Malus domestica) and some Grape (Vitis sp.) vines. These were very fresh and clear to see. Now fast forward to the outing at Kinghurst, where we struggled to find feeding sign on Grape for quite a while. I was excited when we found it.

I love eating the forked tendrils which grow at the ends of the Grape vines as they are crunchy similar to a Japanese Knotweed (Reynoutria japonica) have a slightly sour and bright flavour. I have eaten them on their own and in salads. I bet the Deer would also go for them in the Spring. But do they eat the leaves as well?

11) Hop Hornbeam (Ostrya viriginiana)

I had never seen feeding sign on Hop Hornbeam from an ungulate until this outing. I have seen individual pouches from the hop-like seed clusters opened by Eastern Chipmunks (Tamias striatus) but never had I seen the browsing on the twigs. Since then though, I have seen more ungulate feeding sign, namely Moose (Alces alces) up in Algonquin Park. I wonder if, like Porcupines (Erethizon dorsatum), Deer have specific browse that they tend to have individual preferences for? Do some Deer like the Hornbeam while most don’t find it palatable? Or is it just a case of my not seeing it before as most of the Hornbeams I notice are older, taller and have little to no lower branches within reach of the Deer to browse on?

12) American Beech (Fagus grandifolia)

American Beech seeds are tasty. I have found them hard to gather as a lot of seed cases turn out empty, and a bit tedious to collect so many tiny Beech “nuts” even when the cases are full. It takes a long time to gather even a few seeds. I remember once gathering about a cup of seeds with friends a few years back and between the three of us it took about an hour. I wonder if the Deer can smell it when the seed cases are full versus when they are empty? As for the twig browse, there was only a bit of browse at Kinghurst, but again, in Algonquin the Moose were hitting it pretty hard in some areas.

and one more bonus conundrum…

13) Digging?

I have seen sign of deer digging through the snow to access ferns and acorns before, but in this case there were no Oaks (Quercus sp.) or acorns around that I know of, and I couldn’t see much in the snowy debris of ferns which had been consumed. We were wondering if the deer were searching out roots of some kind, or perhaps they were feeding on some green shoots of grass, which however rare or unusual, has been observed in the past. Because I cannot determine exactly what the deer were after, I have included this as a bonus find, to be observed further in the future.

To learn more :
The Deer of North America by Leonard Lee Rue III. Lyons Press, 1997.
Trees of the Carolinian Forest by Gerry Waldron. Boston Mills Press, 2003.
Animal Skulls by Mark Elbroch. Stackpole Books, 2006.
Deer (The Wildlife Series, Book 3) edited by Duane Gerlach, Sally Atwater & Judith Schnell. Stackpole Books, 1995.

I will do my best to keep this one concise, but covering 4 Ga (four billion years) in a short blog post is going to be a tough one, so please bear with me.

An Introduction

The Beaver Valley was shorn into the land through the cataclysmic pummeling of boulders and rocks propelled by massive riverine torrents spilling from the melting glaciers. Smashing their way across the newly exposed landscape which had been buried under approximately 2 km (~1.25 miles) tall walls of glacial ice, massive boulders, some carried by the ice from thousands of miles away, were being unloaded by the retreating glaciers and hurled across the landscape by epic rivers of incredibly cold meltwaters. These boulders bounced and slammed against the Georgian Bay Shale, and Manitoulin and Amabel Dolostone formations and a few other layers of bedrock before being washed out to the bottom of Georgian Bay, or settling along the valley floor. A broad river, much larger and much more fierce than the present day Beaver River, ran from valley wall to valley wall, eroding rock and depositing till picked up as the glacier repeatedly grew and lurched Southwards and ebbed and waned back Northwards over 2.5 million years of various states of glaciation. This till, carried from as far South as the Appalachian Mountain ranges to the Precambrian volcanic rock of the far North of Turtle Island, was strewn about the valley floor. The area looked like many modern mountain glacial moraines found today, full of rubble and stone, gravel and sands, with no visible life to be seen.

In time, and I mean a long time, wind blown spores of lichens and fungi along with seeds of cold hardy grasses and forbs began to colonize the rubble slowly changing the landscape from stoney valley to something akin to the present day tundra. Seeds of shrubs like willows (Salix spp.) and cottonwoods (Populus spp.) may have been first if we look to the tundra for example, growing quickly and dying back, building up a soil layer more suitable for later post-glacial successi0nal species. A couple of those species were White Pines (Pinus strobus) and Eastern Hemlock (Tsuga candensis) both lightweight wind blown tree species hailing from glacial refugium in Southern Appalachia. Maples (Acer spp.) migrated up from the mouth of the Mississippi, yet took a bit longer than the lighter and hardier conifers. As the world warmed and more faunal visitors returned to the valley, larger seeds were spread. Animals like American Crows (Corvus brachyrhynchos) and Blue Jays (Cyanocitta cristata) would be great acorn and chestnut dispersers, spreading the heavier seeds with their scatter hoarding caching behaviours. I have no records or research, but I bet the Huron-Wendat people who occupied the lands of the Beaver River, and those who likely were there before them, also had a big role in whatever diverse plant species began to spread through the valley. Slowly, very slowly the valley would be transformed into the deep lush forests whose soils and possible seedbank so eagerly desire to reclaim the land if let be.

How Can We Know What Has Happened On The Land By Looking At What Remains?

Dolostone

The photo above is of Marcus sitting against the sheer rock face at the top of Old Baldy. The stone is exposed dolostone which makes up Amabel Dolostone Formation. This dolostone is the product of the bodies of ancient animals which dwelt within the tropical Silurian sea about 450 million years ago.

Wait.. what?

Let me explain.

Dolostone is a sedimentary rock, formed from the calcium carbonate stored in the shells of some ancient brachiopods and cephalopods as well as from the carbonate-secreting algae which lived in a shallow tropical sea some 450 million years ago (mya). At this time our region of Turtle Island/North America was just below the equator and this gave lots of opportunity for ancient sea animals to flourish in the warm waters. The bodies of these animals were made up of the calcium carbonate mentioned above. These bodies which absorbed and used the calcium carbonate to create their hard shells eventually died and sunk to the bottom of the sea. Time rolls on and more and more bodies piled up. More carbonate was released into the aquatic environment Though time and pressure of oceans, through currents and more and more bodies piling up, limestone began to form. As the limestone begins to form a process of dolomitization occurs with the limestone becoming interspersed with magnesium found in the sea water. As the limestone becomes impregnated with the magnesium and the whole solution hardens, it all turns to dolostone.
This dolostone is very similar to limestone, yet with the addition of the magnesium, becomes very durable and is therefore less prone to erosion. While other layers of rock and shale may wash away after 400 million years, the dolostone remains as a remnant sign of the ancient sea beds. As near my home in Guelph, the dolostone cliffs of Old Baldy are like the fossilized dinosaur tracks through ancient creek beds in Texas – remnant traces of life from long long ago.

Glacial Erratics

Throughout the forests of Old Baldy there are many large boulders which do not conform to the dolostone bedrock which underlies everything. They just don’t match up with the rest of the rock that makes up the hill. If the hill is covered in rocks that don’t look like, or aren’t made up of the same stuff as the rest of the hill then we can understand, in tracking terminology, that these boulders are not part of the baseline of the landscape. We can then ask the questions, where are they from and how did they get there?

Some folks used to think that these massive rocks came from the great biblical floods of Noah. Wave action rocked the rocks back and forth for a while until the rocks ended up many thousands of kilometers from where they originated. In a distant sort of way they were right, but instead of water, it was ice.

The most recent glacial advance began about 95,000 years ago and during that period massive lobes of ice advanced Southwards across Turtle Island/North American swallowing and consuming almost everything in their path. As the glaciers covered the landscape, blocks of rock were torn off their home landscapes and carried by the glaciers only to be deposited someplace new. These rocks are called glacial erratics as they are wanderers (errare means ‘wander’ in Latin) across the land. They’re picked up, tossed around and left behind like I do with small sticks and stones on my own wanders. Now the cool thing about these erratics to a tracker might be that if geologists can figure out where the rocks have come from, then they can use these rocks to reconstruct and understand the path that the glaciers took.

I am still new to rock identification and when Alexis and I spoke about the boulder in the photo above, we both knew who to ask for more information: Bill the Bear, retired hydrogeologist and always curious and friendly tracker. I ended up writing him an email and asking what he could tell from looking at a photo of the rock. Turns out he could see a lot.

First he could tell by the colour and texture of the rock that it was likely volcanic in origin and because of that “very very far from ‘home’ ”. He wrote that it was likely composed of iron and magnesium that have been altered by chlorite on the rocks surface as result of being exposed to water over millions and millions of years. He suggested that if his assumptions were correct, then this erratic was likely of Precambrian origin. This would have been “part of the ‘mountain-building’ process, in what is now northern Ontario, which made the Himalayan mountains look like foothills!”
Bill mentioned Precambrian in origin which I think implies that this rock is from the Canadian Shield which is Precambrian igneous rock, which means it was formed between 3.1 Ga (3.1 billion) to the beginning of the Cambrian Period, about 538.8 million years ago. This is a massive span of time, inconceivable to me really, but somehow still awe inspiring. The word igneous means that this rock was “born of fire” or as Bill mentioned, volcanic in origin.
Rocks of volcanic origin are produced in a variety different ways. In the book Ontario Rocks by Nick Eyles, the author states that igneous rocks are formed when magma cools and becomes solid. The grain size of the the rock depends on how fast the rocks cool, with finer grains showing up in rocks that have cooled quickly and course grain in magma that has cooled slowly. This rock was rough to the touch and in my follow up research gets me thinking of a type of rock known as gabbro which is a slow cooling rock formed from molten magma from deep within the Earth’s crust. I have read that these rocks would have become solid more 1 Ga (1,000,000,000, one billion) years ago, and was eventually brought to the Earths’ surface by uplift caused by tectonic shifts and erosion caused by weather, water and wear on the land. Then again the glaciers picked it up and plopped it down at Old Baldy perhaps around 12,000 years ago.

I havn’t been able to figure out more about this rock in particular but I am in search of anything more that might flesh out the details a little more. This might take some time, but I guess that’s what this is all about. The rocks will wait.

Post Glacial Isostatic Adjustment

As mentioned above, the ice sheets around the area of Old Baldy was covered in these massive mounds ice approximately 2km thick. 2000m. 4 CN Towers. 11 Seattle Space Needles. They were @#&$*+!! huge! It’s hard to imagine how tall they must have been, let alone how much they weighed. But they weighed a lot. According to one source, a cubic meter of ice weighs about 916 kilograms (2020 pounds), so it’s kind of interesting to think of what 2000 m of ice might weigh, but really that’s just one spot. Imagine these ice sheets covering all of the Northern parts of Turtle Island/North America and almost the entirety of Canada. To quote Wallace Shawn’s character Vizzini in the 1987 hit The Princess Bride, “Inconceivable!” I can’t find actual numbers but lots of adjectives are thrown around, such as “enormous,” or “massive,” and “incalculable” are a couple of good ones. The glaciers weighed so much that they depressed the Earth’s crust and mantle below. In Northern Ontario near Hudson’s Bay there are estimates that the land was pushed down about 270-280 m (~300 yards), though less in Southern Ontario. This made the land adjacent to these depressions rise as well, like a crest or plate when considering pressure releases in animal tracking.

But something amazing happened as the glaciers started to retreat. The land which had been previously depressed by the incredible weight began to rebound and rise up, and much the adjacent lands which had lifted began to subside (sink down again). This process of rebounding land is called Post-Glacial Isostatic Adjustment. Though it has had many other names over the years such as glacial rebounding, isostatic rebound or crustal rebound, post-glacial isostatic adjustment makes the most sense in that the land isn’t just lifting up again. Some land is subsiding (sinking), some land is being pushed away from where it once was, and this is causing changing sea levels, and even shifting the Earth’s rotation. Post-glacial isostatic adjustment translates to “Changes in equilibrium of the Earth’s crust after the glaciers” which is a more honest and accurate interpretation of what the names are trying to describe. To get back to the point, through these changes of the elevation of the land in the Old Baldy/Blue Mountains area, the land in that area has risen over 15 m since glaciation and is still continuing to rise at a rate of about 15 cm per hundred years or 1.5 cm per decade. It’s not that much in the grand scheme of things, but I still think it’s pretty wild.

When researching geology in the context of tracking the landscape I am reminded of a phrase that Alexis Burnett often attributes to one of his teachers Tom Brown Jr., and I hope I am not misquoting here.. “The Earth longs to be flat, everything else is a track.” A mountain is the track of tectonic plates shifting and smashing into one another, an odd stone in a field the sign of a glacier, and an Oak (Quercus sp.) tree is the remnant sign of a seed possibly dropped by a Blue Jay many years before.
I’ve been thinking about how in a world of calamity and upheaval, extinction and war, that sometimes there is a grounding in remembering the ancient body that we all come from.

Researching and working towards a deeper understanding of the geology of this venerated hill has actually been a peaceful reflection when places of peace have been so hard to find. I recognize that these are epic cataclysmic histories, but the stories held in the stones at Old Baldy have brought about a deep sense of peace for me when it seems so lacking in the world right now. Maybe it’s the disconnect of me not being present for the upheaval and torrent of glacial meltwaters and crushing sheets of ice, but doing the research, piecing together clues, and imagining the magnitude does create a profound sense of wonder and awe, a stupefying amazement in the unveiling of a billion years of mystery written on the body of the hill. I deeply appreciate the work and practice of listening to the stones and tracking the beauty of the land.

To learn more :
Walking Through Time : Exploring Niagara Escarpment Geology in the Beaver Valley Bruce Trail Section by Beth Gilhespy, M.Sc. Self published, 2023.
After The Ice Age : The Return of Life to Glaciated North America by E. C. Pielou. The University of Chicago Press, 1991.
Ontario Rocks by Nick Eyles. Fitzhenry & Whiteside, 2002.
Geology and Landuse Between Guelph and Hamilton: A Self-guided Tour by Chesworth, W., Martini, P., McCarthy, P. and Sadura, S. Dept. Land Resource Science, University of Guelph, 1996.
Ancient Earth interactive globe – see what the Earth looked like from 750,000,000 years ago up to now
NASA’s video on Earth Rebound and Subsidence
Ontario: The Geology of Isostatic Rebound – Rising Land