The M6 motorway nowadays rushes through the Lune Gorge, with the Howgill Fells towering above. These fells are Silurian and Ordovician sandstone and gritstone uplands with distinctive high, rounded ridges and dome-like summits separated by long, steep-sided valleys. The geology is dominated by the turbidites of the Windermere Supergroup, a series of Ordovician and Silurian sediments resulting in a relatively complex series of sequences of sandstone, siltstone and mudstone. The Windemere supergroup is a geological unit formed during the Ordovician to Silurian periods ~450 millian years ago.It underlies much of north England's younger cover, extending south to East Anglia. It was formed as a foreland basin , similar to modern Ganges basin.
To the north of Tebay, around Orton the geology is that of limestone, which is a carboniferous rock. Limestone is a sedimentary rock comprising at least 80% calcium carbonate (CaCO3). Limestones can be deposited in both marine and fresh water environments, the former being more common, the limestone was deposited in the Carboniferous period, over 300 million years ago, and tells us that Britain once lay in warmer latitudes. This tropical environment was similar to the Caribbean of today with lots of algae, corals, and brachiopods.
However, to the south of Tebay there is also limestone, and an example of water erosion. Here the River Lune, which rises in the Howgill Fells ad then flows into Morecambe Bay near Lancaster.
The co-ordinates take you to the Lune's Bridge, an old pack horse bridge across a narrow gorge. From the bridge, you get a good view of the river rushing down the gorge below you. Be careful looking, but down below the river swirls and boils are it goes under the bridge and down the gorge.Sandstone, siltstone and mudstone can vary in colours but tend to range from light buff, through to tan, brown, dark brown and sometimes have orangey red hues, whilst the limestone in this part of Westmoreland tends to vary from a light grey through to grey and also black in some cases.
The river has polished the rocks over the years, and it also has different colours, so the first question I would like you to answer is :
(1) What colour rocks can you see in the gorge, and from this what type of rock do you think it is?
Now as you look downstream, you will see some rock slabs shelving into the water, so the next question is:
(2) What angle are they at in degrees?
Now in my description I mention erosion :
(3) Can you see any evidence of erosion? Please describe the shapes of the rocks and why you think it has been caused by erosion.
Whilst photographs are not obiligatory, I would welcome them in your log. Please do not put the answers in your log, but rather contact me through my profile page. A disabled cacher may be able to access this site.
PLEASE NOTE THERE IS NO NEED TO GO DOWN TO THE SIDE OF THE RIVER. ITS IS SLIPPY AND COULD BE DANGEROUS UNDERFOOT.