2. The Ice Age legacy
What happened to Shropshire during the Ice Age?
The River Severn and the Ironbridge Gorge
Prior to the Ice Age, the River Severn flowed down to Welshpool and then northwards to the present Dee estuary; but when the ice arrived it froze all water and the rivers ceased flowing. As the ice started to retreat at the end of the last Ice Age, the melt water was trapped between the ice front and the high land to the south and east, between Telford, Newport, and Wenlock edge. This created several lakes, which eventually joined to form one lake, covering a large part of the North Shropshire Plain.
From the old Lake bed into the Ironbridge Gorge
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As the lake level continued to rise with the influx of fresh melt water, it began to pour over the lowest part of the high ground in the Buildwas area. Gradually a small valley was cut, and as the lake water continued to discharge with an ever-increasing flow, the present Ironbridge Gorge was created.
As the lake decreased in size, it revealed the old river valleys and the Severn began to run again, but this time it went with the main flow towards Ironbridge and the present course became established.
The Shropshire Lakeland
When the ice sheets advanced, they ground the earth away, pushing huge amounts of soil and rock in front and to the side of them. These piles of "Boulder Clay", known as "Moraines", were then left as low hills and embankments of sand and gravel, with clay beds here and there.
In places, large chunks of ice broke off from the retreating ice front on to these clay beds. They melted slowly and sank into the clay, creating "Kettle Holes", which soon filled with water. These are very evident in the lakes of the Ellesmere area, typically Colemere and Blakemere.
Colemere: Who would believe?
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[Secret Shropshire Image]
Where this type of lake was relatively shallow, it gradually filled in, forming peat bogs. Evidence of this type of action can be found to the east of the general "Mere" area, at Whixall Moss and Wem Moss.
There is much more to know about the the effects of ice on the landscape.
Use your local library to find out about and describe:
- Moraines, eskers and kames
- Upland glaciation and hanging valleys
Find out about Geological forces: Next
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