Chippewa Park

Much of Thunder Bay's waterfront is industrial or otherwise difficult to access.  Marina Park in the north part of downtown was nice, but all riprap.  Chippewa Park south of town has two beaches. The main swimming beach (I guess some people swim in Lake Superior) is a sandy curve along a small cove sheltered by a rock breakwater.

The pictures here are of Sandy Beach, which is more exposed than Chippewa's swimming beach and lies just to the south.  It's the only sand along this stretch, which made me wonder if it could have been trucked in.  The beach is broken into several small curves by rock groins.

This is a uneven stretch of coastline. The adjacent shores are ragged (see aerial below), suggesting that the geology may be irregular (maybe piles of glacial cobble in otherwise soft material, or resistant ledges in softer bedrock). Or perhaps, the shoreline has simply eroded for decades and those little points are old rock groins, sort of like the ones on this beach, but without the sand in between.  I have no idea and only noticed the pattern once I was back in Seattle.

AERIAL VIEW

This beach must be icebound all winter - so wave action is probably most significant in fall before it freezes over.  I don't have enough experience in these settings to know what peculiar things moving ice does to beach gravel, although I assume under certain conditions it can leave some pretty cool landforms - ice thrusts, rafted pebbles, ice scour.

Thunder Bay at hshipman.  As usual, my other blog parallels this one, but instead of rambling commentary about beaches, you get rambling commentary about other stuff.  Sometimes it includes a little non-beach geology; sometimes it just has pictures of food.

Point Pelee

The northern shore of lake Erie (Google Maps) is punctuated by three elegant landforms. The location of each may be determined by glacial features like moraines, but the shape of each is all about wind and waves and moving sediment. There are good bathymetric maps and geologic explanations of Lake Erie at NOAA's NGDC.

Long Point is a spit, neither a simple nor a small one.

Point aux Pins (Rondeau Provincial Park) is an arcuate promontory that might be categorized as a recurved or cuspate spit. Its southeastern shore is composed of a beautiful series of accreted beach ridges, while its western shore is somewhat more tenuous. There is a big offset in the shoreline at the jetties at Erieau and the map on the wall at the Eau Buoy Cafe showed that in 1868 the natural opening was much larger and located pretty much where the town is today.

Point Pelee, where all of the these photos are from, is a large cuspate foreland, tapering to a slender point. It has lost ground, or at least changed shape, over time, making the riprap on the west side of the tip seem both unfortunate and sort of futile. The sinuous tip vanished southward under the waves, tempting me to wade out farther, but the biting flies argued against it.

Point Pelee is the southernmost point in mainland Canada. The country's true southernmost point is a very similar looking spit at the southern tip of Pelee Island, maybe 25 km south of here.

Lake Erie

This is a more geographically general post than most, since my goal was simply to capture several shots taken as we traveled between the Cape Rondeau area and the western end of the lake. This shoreline consists mainly of bluffs, many of clay or silt, but there are also low beaches, including the large barriers that have formed at Point aux Pins and Point Pelee.

The geography of this shoreline appears to be controlled by larger glacial features and sediment variability, subsequently reshaped by Holocene coastal processes. Humans have left their mark, too, with jetties, lots of groins, and a mish mash of armoring, at least locally. Most of the shoreline development is on the low beaches, probably because the bluffs are eroding quickly enough to discourage building and because the demand for Lake Erie view property isn't the same as on Puget Sound.

The timber groins are at Erie Beach?, just west of Erieau (Aerial).
The bluffs are at Point Alma (Aerial).
The sheetpile groins are on the west side of Point Pelee, near Seacliffe. (Aerial)

Sandbanks

Sandbanks Provincial Park, on the northeastern shore of Lake Ontario, includes two large sandy swash-aligned barriers with their accompanying dunes. I had been curious to get here since my 2008 trip to Ontario, when these beaches were just too much to add to one trip. But our route from northern New England to Chicago took us along the northern edge of both Lake Ontario and Lake Erie and Sandbanks was a nice respite from the highway and the muggy, hot weather.

Bluffers Park

Bluffers Park is typical of the large multi-tentacled lake fills found along the greater Toronto shoreline (Humber Bay Park is another). Built as parks, these artificial shorelines are part jetty, part spit, part landfill. Their outer edges consists of revetments, rock headlands, and pocket beaches. They enclose marinas, lagoons, ponds, and marshes. Some of the wetlands have been retrofitted to filter storm water. These are entirely created features and they in no way maintain the natural geological (or ecological, one assumes) processes that originally characterized these shorelines, but they are an interesting approach to creating waterfront access, enhancing habitat, and preventing the historic erosion that would have threatened a growing metropolis.

Scarborough Bluffs

East of Toronto are several miles of high bluffs, apparently a slice across the front of a thick delta deposited long prior to the last glaciation. The toe of the bluffs has been largely stabilized through revetments (both of construction debris and of more of the elegant dolostone seawalls and revetments so common on the lake), groin fields, broad beach fills, and a large lake fill (Bluffers Park). Longshore drift is to the west, so erosion of these bluffs may have fed the spits and shoals that formed the natural precursors to the now heavily modified Leslie Street Spit and the Ontario Islands off the Toronto waterfront.

Cabot Head

Cabot Head lies on a low foreland that extends out in front of the escarpment and that encompasses several wetlands and lakes, including Wingfield Basin, which may have begun as a small lake but is now a lagoon with a shallow entrance to Lake Huron (Georgian Bay).

The gravel road from Dyer Bay out the lighthouse follows a great cobble beach, but what was most amazing was the incredible series of shingle beach ridges on the east side of the point. Shingle - since the rocks are all 6-inch flagstones, all weathered by the several thousand years that has passed since they were last tossed by waves. The fact that they aren't very rounded may indicate that they weren't in the swash zone for very long - a sign of rapidly falling lake levels at the time?

Halfway Log Dump

Early Sunday morning and I have the entire place to myself. This is worth the long weekend, the 2500 mile flight with a coffee stop at O'Hare, the 200 miles of driving, and the 1km walk through the woods. I'd do it again.

Another beautiful gravel/cobble beach on the shores of Georgian Bay. Dolomite ledges to the east with white dolostone cobbles scattered across the surface, lined up in the crevices, and piled against the low seacliff. The broad flat ledge was 1-2 feet above lake level, which made walking the shore simple, but I saw a picture in town yesterday showing the ledges below lake level.

A small sea stack. Ancient white cedars growing out of cracks in the rocks. And a rounded knoll on the platform that I suspect was a particularly dense part of the coral reef that was forming here a mere 400 million years ago.

Singing Sands

The northeastern shore of the Bruce Peninsula is steep, with the escarpment plunging into Georgian Bay. The southwestern shore is low, as the dolostone layers dip gradually into Lake Huron. This leads to an irregular shoreline with promontories and inlets. There's also sand (eroded from glacial deposits on the upland and delivered to the shore by streams), something I didn't see at all on the other side of the peninsula.

Singing Sands is the name given to the dunes and broad beach at the head of Dorcas Bay. The already broad beach is even broader thanks to the recent low lake levels. Plants are already colonizing the new flats. Sand is juxtaposed with the carbonate bedrock. In Hawaii in April, I saw sandy beaches on 120,000 year old limestone (on 5 million year old islands). Here, the beach lies on top of 400 million year old limestone.

Flowerpot Island

The flowerpots are two elegant sea stacks of thinly bedded dolostone on the east side of the island. From the tour boat, I thought the upper surface of the stacks looked suspiciously unnatural and later I read something that indicated that maybe efforts have been made to shore them up. It is always a shame when erosion and the passage of time wipe out the symbol of your community, or the primary destination of your local tour operators! New Hampshire reinforced the Old Man of the Mountain with steel and concrete, though eventually he came down anyway.

Storm Haven

Most folks stick to the simple loop out to Indian Head Cove, the Grotto, and Marr Lake -- lots fewer make the short hike farther east. The trail follows the higher beach ridges and then climbs into the woods and along the cliffs (with some great views), before dropping back down to the cobble beach at Storm Haven.

There were boulders and collapsed chunks of the escarpment in both directions. The beach ridges extend back up the slope and into the trees, the old ridges dating from the higher lake levels of thousands of years ago. The dolostone ledges are thinly bedded and break into angular flagstones which work their way down the beach as talus. They gradually merge with the wave-rounded cobbles that mark the lower beach. It's all the same basic stuff. In the middle, you end up with a nice mixture of angular bricks and rounded cobbles.

The deepest portion of Georgian Bay (170 meters - 560 feet) is located not far from here, and within a couple of kilometers of shore, indicating that the cliffs we see above lake level are just the upper part of a much more extensive landform.

Bruce Peninsula

The Bruce Peninsula is where the Niagara Escarpment slides into Lake Huron (Tobermory is the little town at the tip). It re-emerges a little farther north as Manitoulin Island and separates Lake Huron from Georgian Bay. Its gently rolling surface is marked by wetlands and dolostone barrens called alvars. Unlike the extensive farmland on the glacial deposits to the south, the Bruce is largely forested in pine and white cedar. The steep outer edge of the escarpment forms the northeastern shoreline of the peninsula. The western shoreline slides gradually into Lake Huron.

Niagara Escarpment

The Michigan Basin is underlain by a thick series of very old rocks, including layers of carbonate rocks deposited in warm seas over 400 million years ago. These sedimentary rocks are basically limestone, but the addition of magnesium has turned the calcite to dolomite and the resulting rock to dolostone. These resistant layers are deepest under Michigan, but like a large saucer, tilt gradually upwards until they break the surface in a large arc around the Great Lakes. These rocks form the Niagara Escarpment, a low hogsback (or cuesta) with a gradual slope on the inner (Michigan) side and a steeper cliff or bluff on the outward facing edge.

The escarpment runs from western New York State north into Canada, around the western end of Lake Ontario, and north across the farmland of southern Ontario. It forms the Bruce Peninsula and Manitoulin Island, between Lake Huron and Georgian Bay, and then sweeps across the upper peninsula of Michigan before heading south to form the Dore Peninsula and Green Bay in Wisconsin (thus the geologic similarity of the Buffalo Bills and the Green Bay Packers?). Streams flowing across the escarpment form cascades, Niagara Falls being the most obvious.

Inverhuron

Inverhuron Provincial Park lies north of Kincardine on the southeastern shore of Lake Huron. At Gunn Point, the receding lake had abandoned a nice gravel beach ridge back among the trees and left a broad platform that plants are trying to colonize. On the bay to the south, a nice set of dunes had formed and still farther south, cottages lined a beach with a narrow sandy beach and rock ledges exposed on the recently exposed lake bottom.

Looking north from Gunn Point, I could see Douglas Point and the Bruce Generating Station, the largest nuclear power plant in North America and the second largest in the world (Wikipedia). I suppose it's the existing transmission infrastructure that makes the big wind farm just inland from here possible. I admit, the wind turbines were much prettier in the late afternoon sun than the boxy nuclear plant.

Lake Huron is the third largest lake in the world - and probably larger if you count Lake Michigan, which is really part of the same lake. It's been ratcheting downward for thousands of years, although relatively high water in the 1980s caused lots of erosion problems. The last few years it has continued to fall and is near record levels now. This is partly due to regional hydrology - maybe less rain - but it may also be due to human changes at the outlet near Detroit. Once again, we can credit regional changes in the environmental landscape to the Corps of Engineers!