(upbeat music)
F1: This is Cwm Llwch in The Brecon Beacons National Park.
(quiet music)
Now, whether we call it a cwm in Wales,
a corrie in Scotland, or a cirque in France,
it all refers to the bowl
or the amphitheater-shaped hollow at the
head of a glacial valley.
And this is where the glacier began.
During the last ice age, snow fell and accumulated,
piling up in the hollow here,
and it became compressed into ice.
Under its own weight, the ice slowly started creeping
down the valley, at a rate of about one metre per day,
carving out this armchair-shaped hollow in the mountain.
Now there's a big cwm here, but within it is a smaller
cwm on the other side of the valley just behind me.
And this was created by a little glacier,
right at the end of the last ice age.
(gentle music)
Within the hollow of this little cwm,
water has accumulated creating a lake called
Llyn Cwm Llwch, that was created by material
or moraine, deposited by the glacier.
(upbeat music)
And in glaciology, we call these
little lakes corrie lakes or tarns.
(upbeat music)
M1: Thank you to Oldham Hulme Grammar School
for helping to support this Time for Geography video.
To find out how your school can help
support Time for Geography
and have a shout-out on one of our videos,
visit the patrons page of our website.