One hundred years ago geologists thought the Earth's crust was like the shell on an egg. Then during the past 50 years they came up with Plate Tectonics1. Apparently at one time the pastures of Yorkshire were on one plate and Cumbria was on another. Where these plates met there are a series of geological fault lines.
According to the USGS2 glossary of terms, a fault is 'a fracture along which blocks of crust on either side have moved relative to one another parallel to the fracture'.
At the Sedgwick Geological Trail, small areas of these blocks of crust have been exposed by the river, and the strata here is clearly visible. This trail is located on the Dent Fault where it crosses the River Clough in Cumbria and is named after a 19th-Century geologist, Adam Sedgwick.
Location
The trail is located at the bottom of a hill on the A684 near Sedgbergh, England3. Today, this is a barely marked footpath in a sheep pasture (Langstone Fell). Assuming the trail is still open to the public, you should watch your step when you go there, because the sheep are still there doing what sheep do. Amateur geologists (known as 'Rock Hounds') come here to see the rock where it has been cut by the river, exposing the various layers. 330-million-year-old synclines4 and folds are visible and the nature of the rock changes abruptly as the river crosses the Dent fault.
During what some have called the golden age of geology in Britain, Sedgwick walked in this pasture and noticed the fault. He went on to become a renowned geologist at Cambridge University. This trail was made during the 1980s to commemorate him.
Finding the Trail
Park on the A684 in the gravel car park at the top of the hill. Walk the finished path which leads to the right down the hill. At the river, before crossing the footbridge, turn left onto the grass. Now you are on the Sedgwick Geological Trail. Weatherbeaten wooden posts are numbered with points on the trail. Not all of them are easy to spot. What is easy to see is the river and the strata of the rock on the opposite shore. If you look closely, you can almost tell where you have crossed the fault, because the nature of the rock along the riverbank changes. At the end of the trail there is a steep climb back to the car park.
1 For more on Plate Tectonics read This Dynamic Earth or BBC Bitesize
2 The United States Geological Survey
3 Map reference GR695912, Sheet reference 98 in the Ordnance Survey Landrangers 1 to 50,000 Series.
4 Synclines are where the beds of rock dip towards each other.
