0:00:05.967,0:00:12.671
Speaker: Okay, so this is the difference [br]between uh, glacial till,

0:00:12.671,0:00:14.573
which is unstratified,

0:00:14.573,0:00:16.924
and non-glacial till.

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So, hopefully you can see [br]that this, uh, gravel here

0:00:21.248,0:00:23.333
is well-stratified.

0:00:23.333,0:00:26.053
There are a lot of [br]sedimentary features here.

0:00:26.053,0:00:31.090
Um, you can see graded bedding.

0:00:31.090,0:00:33.243
You can also see cross bedding.

0:00:33.243,0:00:36.996
Maybe I can just sort of zoom in on that.

0:00:36.996,0:00:39.633
So there's cross bedding right there.

0:00:39.633,0:00:43.719
Very coarse uh, cross bedding.

0:00:43.719,0:00:47.506
However, the stratification [br]or the horizontal layering,

0:00:47.506,0:00:49.442
the general horizontal here,

0:00:49.442,0:00:53.529
indicates that this is not glacial gravel.

0:00:53.529,0:00:55.864
Even though it's approximately [br]the correct size

0:00:55.864,0:00:59.402
and sorting distribution.

0:00:59.402,0:01:01.705
The presence of sedimentary features

0:01:01.705,0:01:04.762
as well as, uh, the stratification,

0:01:04.762,0:01:06.380
that's the horizontal layering,

0:01:06.380,0:01:09.718
indicated as not glacial gravel.

0:01:09.718,0:01:13.438
Okay. I'll try and show you[br]glacial gravel a little later.

0:01:13.438,0:01:16.958
So this is uh, glacial till.

0:01:16.958,0:01:20.445
It is gravel that is deposited [br]by a glacier.

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Um, and the identifying[br]characteristics of it

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is well-rounded clasts,

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however they're not[br]really really well-rounded.

0:01:34.392,0:01:37.812
They are definitely rounded [br]to some extent.

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Um, oftentimes there are striations [br]on each individual clast,

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maybe I can show you that later.

0:01:43.166,0:01:46.271
Um, those are scratches that are produced

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when gravel bounces or scrapes against

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other pieces of gravel or the bedrock.

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And the other identifying characteristic

0:01:52.827,0:01:56.814
is that the gravel itself [br]is unstratified.

0:01:56.814,0:02:01.569
There is no layering, [br]no horizontal stratification.

0:02:01.569,0:02:04.755
Um, and there really are [br]no sedimentary features here,

0:02:04.755,0:02:07.425
other than the lack [br]of sedimentary features,

0:02:07.425,0:02:11.579
which indicates that [br]it was deposited by a glacier.

0:02:11.579,0:02:14.164
Now hopefully you'll be able to see,

0:02:14.164,0:02:16.217
if it'll focus on that,

0:02:16.217,0:02:21.088
the scratches [br]on the surface of this clast.

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Those parallel scratches [br]are glacial striations,

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which are present on a clast.

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It's stuck in there pretty hard. Argghh.

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It won't come out.

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And in addition to the lack of uh, [br]sedimentary features,

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um, one of the characteristics [br]that you always look for

0:02:54.348,0:02:57.135
is a very very poor degree of sorting

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in terms of clast size.

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And so, maybe I can [br]zoom in on that a little bit.

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You've got clasts of all different, [br]uh, sizes.

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Very poorly distributed.

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I suppose even down to these sizes,

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which have fallen down [br]from the cliff face, I suppose,

0:03:26.096,0:03:29.351
the gravel face anyways.

0:03:29.351,0:03:31.503
Very poor sorting.

0:03:31.503,0:03:33.355
Okay. Since we're talking about till,

0:03:33.355,0:03:36.825
I thought I'd show you [br]what happens when till, um,

0:03:36.825,0:03:41.312
becomes a rock, when it becomes [br]consolidated or indurated.

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This is called tillite, which is uh,

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the rock, I suppose, from glacial till, [br]a conglomerate.

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This one is very old.

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It is on the side of [br]the Trans Canada, here. [cars going by]

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As you can tell by the traffic.

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And it is south of[br]Wawa in Ontario, Canada.

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[traffic in background]

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This particular crop has been [br]highly metamorphosed,

0:04:12.793,0:04:14.962
so these in the Canadian shield.

0:04:14.962,0:04:18.766
Um, so strongly metamorphosed.

0:04:18.766,0:04:21.418
And this tillite is uh, [br]weathering very rapidly

0:04:21.418,0:04:23.905
as a result of the intense metamorphism,

0:04:23.905,0:04:26.506
which has caused cracks and fractures

0:04:26.506,0:04:28.776
which increase surface area, of course,

0:04:28.776,0:04:30.927
and cause weathering to accelerate.

0:04:30.927,0:04:35.866
[traffic in background]

0:04:35.866,0:04:37.868
Now realize I'm looking at a shadow here,

0:04:37.868,0:04:43.257
but hopefully you can see [br]that the clasts are well-rounded.

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Very poorly sorted, [br]in terms of size distribution.

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And are not layered.

0:04:51.128,0:04:53.063
They are unstratified.

0:04:53.063,0:04:56.285
I just thought you might want to see [br]what's on the other side of the road.

0:04:56.285,0:04:59.820
That is Lake Superior,

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about an hour south of Wawa, Ontario.

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Pretty big lake, eh?

0:05:05.660,0:05:11.077
Kind of looks like the ocean.

0:05:11.077,0:05:12.948
You can't see the other side [br]of Lake Superior,

0:05:12.948,0:05:17.084
even though we're way the heck up [br]on the roadside.

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There you can see down to the beach.

0:05:23.109,0:05:24.483
Alright, that's it.

0:05:24.483,0:05:27.429
Bye for now.