The Geology:
A gorge is a narrow valley with steep, rocky walls located between hills or mountains. The term comes from the French word gorge, which means throat or neck. A gorge is often smaller than a canyon, although both words are used to describe deep, narrow valleys with a stream or river running along their bottom.
A number of natural forces form gorges. The most common is erosion due to streams or rivers. Streams carve through hard layers of rock, breaking down or eroding it. Sediment from the worn-away rock is then carried downstream. Over time, this erosion will form the steep walls of a gorge. The flooding of streams or rivers increases the speed & intensity of this erosion, creating deeper & wider gorges.
The movement & melting of glaciers can also produce gorges. Glaciers cut deep valleys into the Earths surface. These rivers of ice can create huge canyons & sharp, steep gorges. As glaciers melt, or retreat, these gorges & canyons are exposed. Indication that a gorge has been formed in this manner, is the presence of glacial erratics. A glacial erratic is a piece of rock that has been transported by a glacier, when the glacier melts, the rock is deposited somewhere. It will normally differ from the size & type of rock native to the area in which it rests.
Engineers have purposely flooded gorges by creating dams. These dams are used to generate hydroelectricity (the production of electrical power through the use of the gravitational force of falling or flowing water). As far as I am aware, there isn't a dam planned for Broadbottom.
Many geological discoveries have been made at gorges, because gorges often expose layers of rock that go back millions of years.
The Gorge:
To reach the given co-ords, walk up Hague Road from the suggested parking area. To your right, you'll see the easy climb up point onto the rock outcrop. Once up there, not only will you be greeted by one of the best views of the gorge, but also the scary looking view down ;-) If you take your kids or dogs up onto the rocks, make sure they are kept well away from the edge, as a fall from here would be fatal.
Best Hill Mill (before the viaduct was built) |
To your right, you'll see the impressive Broadbottom Viaduct (also known as Etherow Viaduct). It's a railway viaduct that spans the River Etherow between Derbyshire & Greater Manchester. Originally of wooden construction supported by stone piers, the timber was replaced first with wrought iron girders, less than 20 years after the viaduct's opening, & later with riveted steel girders. It is now a Grade II listed building.
At the bottom of the gorge, you will see/hear the river Etherow meandering along. The Etherow flows through South Yorkshire, Derbyshire & Greater Manchester, before joining the River Goyt near Marple.
To the left of the cottages below you, was where Best Hill Mill once stood (pictured). The weir for the mill can still be found just upstream. There was another large mill 0.4 miles upstream from here, called Bank Wood Mill. Lymefield & Broad Mills were downstream from here - there's a Heritage Site there, that is well worth a visit.
Go to the related web page to see photos I've taken of the gorge.
The Questions:
In order for you to log a find, you need to answer the following questions:
- As you stand on Hague Road looking at the easy climb up point, there's a much taller bit of rock to the left. Estimate its full height above Hague Road.
- When stood on the rock outcrop, estimate how high you are above the river. (The internet could help with this one)
- The rock outcrop you're stood on contains two large pieces of rock (boulders). Compare the texture & colour of them to the texture & colour of the exposed rock of the outcrop. Are they the same type of rock, or do you think they are glacial erratics? If they aren't glacial erratics, why do you think they are here?
- How do you think this gorge was created?
Any accompanying photos are welcome, as long as they don't give away the answers to Q1 & 3.
Please send your answers to me via my profile. If you could send your e-mail at the same time as you log your find, that would help immensely. If your answers aren't received within a month, your log will be deleted (you would be contacted prior to this happening).