Tuesday, March 27, 2012

The Birds are Back too Early!

Two weeks of warm weather before we even got to the last week of March, and a lot of the spring birds are probably very confused. At least they've arrived back far earlier than usual.

We had the robins, grackles, red-wings and turkey vultures on time, in the 2nd week of March, but in the next week we had song sparrows, flickers, and our favourite blue jay, all of which don't usually arrive back til the 2nd week of April! I just hope the returning cold weather doesn't do them in.

Saturday, March 24, 2012

Another Waterfalls - Webwood Falls

Webwood Falls, on a property newly donated to the Bruce Trail Conservancy, is another falls formed by the Manitoulin Formation. It was also the site of an old mill many years ago, a small wall of which remains. The stream flowing over the falls has carved out a deep, steep-sided gorge in the easily eroded Queenston Shale downstream.

In the closer view below you can see the thin limestone layers of the Manitoulin Formation, as well as the Ordovician shale below, in this location a bluish grey colour.

Webwood Falls is located on the 25th Sideroad east of County Rd. 7, one concession south of County Rd. 40. Unfortunately the falls faces directly away from the road, though it's only perhaps 50 feet away. You'll have to get out of your car to see it.

Friday, March 23, 2012

Hidden Waterfalls

Waterfalls in the Beaver Valley don't always fall from the top of the Escarpment. In fact, there may be more waterfalls created by the Manitoulin Formation that by the higher rock layers. This one, a short distance south of Johnson's Sideroad, is along the 'Falling Water Trail', that part of the Bruce Trail extending south of Bowles Hill,

Visiting some of the waterfalls along the trail may be one of the easiest places to see the Manitoulin Formation up close.

The thin limestone layers of the Manitoulin Formation form the hard upper layer, over which this waterfalls plunges.

At the bottom of the falls, the very top of the Ordovician Formation, here a dark reddish shale, is exposed.

In the winter, this falls was just a vertical curtain of ice; by now it will be flowing heavily.

Thursday, March 22, 2012

The Beaver Valley's Double Escarpment Part II

To understand the seconday escarpment formed by the Manitoulin Formation, you need to understand the layers in between. At the top of the sequence are the thick layers of Amabel or Lockport dolomite that form the main cliffs of the Niagara Escarpment, especially up the Bruce Peninsula (not visible in this picture). Below this, after a few narrow bands collectively known as the Clinton Formation, is the Cabot Head Formation. In this picture, it forms the relatively gentler slope below the hydro towers, but above the short Manitoulin cliff. It is mainly composed of shale, which is relatively soft and therefore erodes to form a slope rather than a vertical cliff.

The Manitoulin Formation below it is limestone, which is much harder, and therefore does form the short cliff in the middle of the slope. Together, the Cabot Head and Manitoulin Formations are sometimes known as the Cataract Formations. Below this is the long steep slope of the Queenston Formation, another shale. Because it erodes steadily, and is a very thick formation, it always forms a long slope below the escarpment cliffs. It is made up of the red and sometimes bluish clay that is occasionally exposed in roadcuts or at the base of waterfalls.

So the entire escarpment is made up of hard, soft, hard and soft layers in a sequence; this accounts for the Beaver Valley's double escarpment. You can see this whole sequence in this picture, with an outcropping of the upper Amabel cliffs in the far left of the picture, the short Cabot Head slope below this, the flat line of the Manitoulin Formation across the centre of the photo, and the long steep slope of Queenston shale below that, right down to the river.

You don't often actually see the Manitoulin cliff when hiking the Bruce Trail, because if it is exposed, you are likely walking on top of it. For the entire stretch shown in this picture above, south and north of the hydro towers, the trail follows right along the top of the Manitoulin Formation.

You can also see the Manitoulin Formation easily in Owen Sound, if you drive west on 10th Street from the downtown. A few blocks west of the river, you drive up a hill through a rock-cut; this is the Manitoulin Formation. After driving west through the 'sunset strip', you come to a second cliff, where the Bruce Trail crosses. This is the higher level, the Amabel or Lockport dolomite cliff.

Wednesday, March 14, 2012

The Beaver Valley's Double Escarpment

For several years I've been intrigued with the very flat line of rocks that you see in front of you on the east side of the Beaver Valley when you drive down Bowle's Hill. It extends north and south of the power plant with it's well known towers, forming a flat geological layer about one-third of the way down the slope. In this picture, taken half-way down Bowle's Hill, you can easily see the perfectly flat line of the rocks. You can see that the power plant flumes actually bend at this point in the slope as they descend over a short cliff - but this is not the thick limestone caprock that forms the top of the Niagara Escarpment.

After reading all I could find out, I've learned that this is the Manitoulin Formation, a layer of limestone rocks that creates a short secondary cliff in this part of the larger Niagara Escarpment. The next picture below illustrates this limestone layer up close, as it appears at the top of a waterfall further south on the west side of the valley.

You can see that this formation is composed of thin bands of limestone, in contrast to the huge thick blocky rocks of the Old Baldy cliffs, shown below. The Manitoulin Formation limestones are strong enough to form a short cliff, but not nearly as strong as the Amabel or Lockport Formation which forms Old Baldy.

The origins of the two formations are very different as well. The Manitoulin Formation was formed as part of a huge delta, laid down across southern Ontario by rivers flowing west from the Taconic Mountains, the original Appalachians, once as high as today's Himalayas. This is why it appears as a flat line on the escarpment slope. The cliffs of Old Baldy, in contrast, were formed as coral reefs around the outer edge of the Michigan Basin some 400 million years ago. Later infused by magnesium-rich water, and hardened into rock, they are in effect one huge thick layer, forming the cap-rock of the Niagara Escarpment. They also vary in height, because the coral reefs were of course thicker and higher in some places than others.

In this last picture you can see both the cliffs of Old Baldy and the flat line of the Manitoulin Formation, slightly below and to the left of the open cliffs, about one-quarter of the way down the slope. You have to look carefully to pick it out, extending to the left, but disappearing beneath the talus slopes below Old Baldy on the right. The whiter area below is not a geological formation, but a former farm field, not yet much grown up in trees.

The Manitoulin Formation in effect forms a double escarpment, a set of smaller cliffs lower down the slope than the big caprock cliffs. So if you're driving down Bowle's Hill, watch the east slope in front of you for the Beaver Valley's double escarpment.

Sunday, March 11, 2012

First Robin!

This morning the first robin of the season was sitting in a tree across from our place, singing merrily. And the day that followed suited it, as it rose to nearly 16, a beautiful warm spring day. Winter is definitely over now.

Saturday, March 10, 2012

Winter Goes; Winter Comes Again

Last Monday and Tuesday were about the best winter we've had all winter! But then came the soaring temperatures of Wednesday, and winter effectively disappeared, still white, but the snow much reduced, and the driveway actually bare. I thought spring had arrived. Then yesterday winter came back with a vengeance, in a cold blustery day with strong winds, cold temperatures and lots of snow. Looking out today we're back to winter, a bonus for the ski clubs at the beginning of March Break.

One of my favourite winter pictures comes on a sunny day when you see bluish shadows across the snow when walking the trail. These two pictures were taken on the Sligo side trail a week ago.

Tuesday, March 6, 2012

Planetary Brilliance!

Last night was a beautiful moonlit night with a clear sky, and the visible planets are at their best - in fact, March 2012 is going to be the best planet viewing month we've had for a long time - if you get a clear night.

In the early evening, about 8 p.m. last night, both Venus and Jupiter were shining brightly in the western sky. They'll be visible all month there, with a rare conjunction of these planets on Mar. 15th, when they are very close together (to our eyes). Until then Jupiter is the higher one of the two; after that Venus will be higher in the sky.

But that's not all. Mars rises in the east in early evening, and stays visible most of the night, nearly overhead by 11 p.m. It's as bright as any start in the eastern sky and has a bit of a reddish tinge. It's at the closest point of its orbit to earth, so it's particulary bright this month.

And later in the evening, sometime before 11 p.m., Saturn rises in the east. It's not as bright as the others, but clear to see if you watch for it.

If you want to read more, just google 'planets tonight' and read about it. But watch for a clear evening, and take advantage of the chance to see four planets in one night. If you're lucky you might even see a fifth, Mercury, just barely visible in the western sky 45 minutes after sunset, about where the sun sets, and below Venus and Jupiter - but it disappears quickly.

Saturday, March 3, 2012

Winter's First Blizzard

Woke up to a howling blizzard this morning, a good day to just stay inside.

Yesterday we took off and went to the Stratford Garden Festival, always a nice taste of early spring. It was above freezing, almost warm, and little snow down there. It started raining as we got home, and rained heavily in the evening - leaving me afraid the driveway would turn to ice again if it froze.

The forecast was for rising temperatures overnight and more rain, which may have happened for awhile, but then the cold front obviously came through and it all froze, with heavy strong winds and snow following. So today we look out at a blizzard of white, the worst storm we've had all winter. .......

...... This morning it's a different world, sunny with only thin cloud cover, and lots of snow. The winds died by 4 in the afternoon, but the lake streamers continued well into the evening, snowing quite heavily at times. So today we have a fresh 6 - 10" everywhere.