Jackson, Ian. Cumbria Rocks — 60 extraordinary rocky places that tell the story of the Cumbrian landscape. Newcastle upon Tyne : Northern Heritage, 2022. The richly illustrated and accessible book series of Cumbria, Northumberland and Durham Rocks are available to purchase from Northern Heritage.
33 Trusmadoor
Theme: Earthquakes and folded rocks
Location
33 Trusmadoor — Skiddaw Group sediments and graptolites. A 7 kilometre return hike up Longlands Beck or 12 kilometres across Great Sca Fell from Fellside
Description
Tucked away in the northern fells is a beautiful little valley with a unique name and two rock stories to tell …millions of years apart.
Trusmadoor — the first two syllables of its name are rare — Trus and ma are from an ancient Celtic language called Cumbric, used in the kingdoms of Cumbria after the Romans. The whole word is literal, it means place of the mountain gap to which the English word ‘door’ has been added.
The rocks in the crags on the valley side are slates. They are from the Skiddaw Group which makes up most of the northern Lake District and of course the mountain they are named after, Skiddaw itself. Their formal geological name used to be Skiddaw Slates but not all the rocks are slate so geologists changed the name. During the Ordovician these rocks were mud, silt and sand in a deep ocean. Millions of years of being buried and heated deep in the Earth, and then uplifted, broken up and eroded, has produced the rocks and the rounded hills we see today. Life on Earth was primitive 480 million years ago and existed mainly in the sea. Fossils from some of those primeval animals, called graptolites, have been found in the slates at Trusmadoor. The way graptolites changed their shape as they evolved has helped palaeontologists to unravel the sequence and development of life on our planet back then.
Move forward to just 15,000 years ago. Glaciers which had occupied Lake District valleys for many thousands of years were melting; torrents of water and debris draining under and out of the ice cut channels in the bedrock. Trusmadoor is one of those Ice Age channels, left high, dry and hanging now. Alfred Wainwright described Trusmadoor more dramatically ‘a lonely passage between the hills….a natural railway cutting. What a place for an ambush and a massacre’.