5 Kingswood ridge
Looking down on the landslide. The ground has a hummocky appearance and the type of vegetation suggests wet ground with poor drainage. The rock beneath here contains a lot of clay. Water combined with clay makes for surfaces that easily slide. The sliding, or slumping, is best seen from below looking up.
What type of rock is beneath you now? Knowing where there are rocks which may give rise to slumping ground and unstable slopes, is very important to engineers, when making roads, railways and buildings. The hill sides of Ankerdine Hill, just a short way south from Martley, slip a lot. You can see trees there sloping, as the ground around them gradually slides away towards the A44 road.
Kingswood landslide from bottom of slope
This view is from the path at the bottom of the slope. You can see how chunks of the ground have slid, leaving behind C shaped scars
The slippage results from a combination of the existence of rock rich in clay minerals, which is made slippery by rainwater, together with fracturing of nearby rocks.
This shows a slump extending from just below where you are now standing all the way down the slope towards the river.
The public footpath that runs along the side of the river through Kingswood has had to be closed as it has essentially slid into the river! The northward drift of the Avalonia plate has carried the crust where you now stand from near the south pole to where it is now. Such processes that move continents are difficult for us to imagine or to see direct evidence of them happening, but happen they do!
Route to next site
Walk back a short distance along the path to you reach the gate and stile. Go through the gate and follow the track along the side of the field.
Route to next site – 6
The path swings around to your left and enters a big wide open field. The path cuts through whatever crop may currently be growing in the field. Site 6 lies ahead along the path at about the highest point in the field.
Task Site 5 Question
Parts of this grassy slope has slipped downhill leaving bare semi-circular scars on the slope. Do you think this is because the rocks here:
a) contain slippery clay
b) let water through
c) are fractured
d) all of these