9:59:59.000,9:59:59.000
Okay, so this is the difference between uh, glacial till,

9:59:59.000,9:59:59.000
which is unstratified,

9:59:59.000,9:59:59.000
and non-glacial till.

9:59:59.000,9:59:59.000
So, hopefully you can see that this uh, gravel here

9:59:59.000,9:59:59.000
is well-stratified.

9:59:59.000,9:59:59.000
There are a lot of sedimentary features here.

9:59:59.000,9:59:59.000
Um, you can see graded bedding.

9:59:59.000,9:59:59.000
You can also see cross bedding.

9:59:59.000,9:59:59.000
Maybe I can just sort of zoom in on that.

9:59:59.000,9:59:59.000
So there's cross bedding right there.

9:59:59.000,9:59:59.000
Very coarse uh, cross bedding.

9:59:59.000,9:59:59.000
However, the stratification or the horizontal layering,

9:59:59.000,9:59:59.000
the general horizontal here,

9:59:59.000,9:59:59.000
indicates that this is not glacial gravel.

9:59:59.000,9:59:59.000
Even though it's approximately the correct size

9:59:59.000,9:59:59.000
and sorting distribution.

9:59:59.000,9:59:59.000
The presence of sedimentary features

9:59:59.000,9:59:59.000
as well as uh, the stratification,

9:59:59.000,9:59:59.000
that's the horizontal layering,

9:59:59.000,9:59:59.000
indicated as not glacial gravel.

9:59:59.000,9:59:59.000
Okay. I'll try and show you glacial gravel a little later.

9:59:59.000,9:59:59.000
So this is uh, glacial till.

9:59:59.000,9:59:59.000
It is gravel that is deposited by a glacier.

9:59:59.000,9:59:59.000
Um, and the identifying characteristics of it

9:59:59.000,9:59:59.000
is well-rounded clasts,

9:59:59.000,9:59:59.000
however they're not really really well-rounded.

9:59:59.000,9:59:59.000
They are definitely rounded to some extent.

9:59:59.000,9:59:59.000
Um, oftentimes there are striations on each individual clast,

9:59:59.000,9:59:59.000
maybe I can show you that later.

9:59:59.000,9:59:59.000
Um, those are scratches that are produced

9:59:59.000,9:59:59.000
when gravel bounces or scrapes against

9:59:59.000,9:59:59.000
other pieces of gravel or the bedrock.

9:59:59.000,9:59:59.000
And the other identifying characteristic

9:59:59.000,9:59:59.000
is that the gravel itself is unstratified.

9:59:59.000,9:59:59.000
There is no layering, no horizontal stratification.

9:59:59.000,9:59:59.000
Um, and there really are no sedimentary features here,

9:59:59.000,9:59:59.000
other than the lack of sedimentary features,

9:59:59.000,9:59:59.000
which indicates that it was deposited by a glacier.

9:59:59.000,9:59:59.000
Now hopefully you'll be able to see,

9:59:59.000,9:59:59.000
if it'll focus on that,

9:59:59.000,9:59:59.000
the scratches on the surface of this clast.

9:59:59.000,9:59:59.000
Those parallel scratches are glacial striations,

9:59:59.000,9:59:59.000
which are present on a clast.

9:59:59.000,9:59:59.000
It's stuck in there pretty hard. Argghh.

9:59:59.000,9:59:59.000
It won't come out.

9:59:59.000,9:59:59.000
And in addition to the lack of uh, sedimentary features,

9:59:59.000,9:59:59.000
um, one of the characteristics that you always look for

9:59:59.000,9:59:59.000
is a very very poor degree of sorting

9:59:59.000,9:59:59.000
in terms of clast size.

9:59:59.000,9:59:59.000
And so, maybe I can zoom in on that a little bit.

9:59:59.000,9:59:59.000
You've got clasts of all different, uh, sizes.

9:59:59.000,9:59:59.000
Very poorly distributed.

9:59:59.000,9:59:59.000
I suppose even down to these sizes,

9:59:59.000,9:59:59.000
which have fallen down from the cliff face, I suppose,

9:59:59.000,9:59:59.000
the gravel face anyways.

9:59:59.000,9:59:59.000
Very poor sorting.

9:59:59.000,9:59:59.000
Okay. Since we're talking about till,

9:59:59.000,9:59:59.000
I thought I'd show you what happens when till, um,

9:59:59.000,9:59:59.000
becomes a rock, when it comes consolidated or indurated.

9:59:59.000,9:59:59.000
This is called tillite, which is uh,

9:59:59.000,9:59:59.000
the rock, I suppose, from glacial till, a conglomerate.

9:59:59.000,9:59:59.000
This one is very old.

9:59:59.000,9:59:59.000
It is on the side of the Trans Canada, here. [cars going by]

9:59:59.000,9:59:59.000
As you can tell by the traffic.

9:59:59.000,9:59:59.000
And it is south of Wawa in Ontario, Canada.

9:59:59.000,9:59:59.000
[traffic in background]

9:59:59.000,9:59:59.000
This particular crop has been highly metamorphosed,

9:59:59.000,9:59:59.000
so these in the Canadian shield.

9:59:59.000,9:59:59.000
Um, so strongly metamorphosed.

9:59:59.000,9:59:59.000
And this tillite is uh, weathering very rapidly

9:59:59.000,9:59:59.000
as a result of the intense metamorphism,

9:59:59.000,9:59:59.000
which has caused cracks and fractures

9:59:59.000,9:59:59.000
which increase surface area, of course,

9:59:59.000,9:59:59.000
and cause weathering to accelerate.

9:59:59.000,9:59:59.000
[traffic in background]

9:59:59.000,9:59:59.000
Now realize I'm looking at a shadow here,

9:59:59.000,9:59:59.000
but hopefully you can see that the clasts are well-rounded.

9:59:59.000,9:59:59.000
Very poorly sorted, in terms of size distribution.

9:59:59.000,9:59:59.000
And are not layered. They are unstratified.

9:59:59.000,9:59:59.000
I just thought you might want to see what's on the other side of the road.

9:59:59.000,9:59:59.000
That is Lake Superior,

9:59:59.000,9:59:59.000
about an hour south of Wawa, Ontario.

9:59:59.000,9:59:59.000
Pretty big lake, eh? Kind of looks like the ocean.

9:59:59.000,9:59:59.000
You can't see the other side of Lake Superior,

9:59:59.000,9:59:59.000
even though we're way the heck up on the roadside.

9:59:59.000,9:59:59.000
There you can see down to the beach.

9:59:59.000,9:59:59.000
Alright, that's it. Bye for now.