This EarthCache will take you to Croft Pasture nature reserve which is managed by the Leicestershire and Rutland Wildlife Trust. The nature reserve is declared a Regionally Important Geological Site (RIGS) and Site of Special Scientific Interest (SSSI). This amazing Geological site was formed by a glacier (a slowly moving river of ice) moving through the area during the Anglian glaciation (about 480,000 years ago).
The nature reserve hosts some important geological features, including this superb example of a Roche Moutonnée. a rock formation that has been formed from glacial erosion.
Dogs must be on a lead due to the possibility of livestock being present.
The area can get quite muddy in wet weather so make sure you have suitable footwear.
The EarthCache can be accessed all year round and is best visited in the Summer to view the rare plants within the reserve.
Directions
Street parking is available on Hill Street (waypoint P0), or alternatively outside the Heathcote Arms pub, or church, which are both located on the adjacent minor road.
Walk up Station Road to the entrance track which is on the right-hand side of the road (waypoint T0). A short walk up the track will lead you to a kissing gate and information board for the nature reserve. After passing through the gate, take the footpath to the right which will lead you to the EarthCache after a 10-minute walk. The Roche Moutonnée is located on the Northern side of the river, after just passing over the lovely bridge.
What is a Roche Moutonnée?
A Roche Moutonnée is a rock formation that has been formed by the passing of a glacier. As the glacier calves its way across the landscape, eroding the ground as it moves, the glacier reaches an obstruction, in this case a harder layer of bedrock. The movement of the glacial ice over bedrock results in two distinct erosional forms. The upstream (also known as 'Stoss') side of the rock is subjected to abrasion from the glacier, resulting in a smoother half and the downstream (also known as 'Lee') side of the rock is subjected to 'plucking', resulting in a more jagged half.
Upstream 'Stoss' side of the rock
When the glacier reaches the rock, the glacier is forced up and over the rock and in doing so high pressure is exerted causing the base of the glacier to melt, allowing the glacier to move over the rock more freely. Under pressure, rock fragments and sand carried by the glacier on this uphill section of the rock smooth the side of the rock resulting in a gentle incline and smooth rock surface.
Parallel scratches can sometimes be seen along the surface of the rock, these are known as striations. The striations are formed due to the abrasion of rock fragments and sand carried by the glacier under pressure scratching the rock as the ice moves across the surface.
Downstream 'Lee' side of the rock
On the lee side of the rock as ice moves downstream, pressure decreases since less energy is needed and the meltwater base of the glacier refreezes. A combination of the refreezing meltwater and the refreezing of meltwater that had previously seeped into cracks within the rock, causes masses of rock fragments to be ripped away as the glacier moves downstream, plucking the rocks below it. This leaves a steeper, more jagged end to the Roche Moutonnée.
A Roche Moutonnée can be as small as a metre in size to as large as several hundred metres. Here at the nature reserve is a superb example of a relatively small Roche Moutonnée. By examining Roche Moutonnées, scientists can reconstruct the flow and direction of former glaciers.
How to claim a find for this EarthCache
In order to claim a find on this EarthCache please answer the following questions and send your answers through my geocaching profile, email or message centre.
The questions assume your viewpoint from the EarthCache coordinates. Remember, there are not always right or wrong answers, as some questions are to get you thinking about why something might be the case, but we hope you enjoy the experience, enjoy a healthy discussion, and learn something new.
1) From your viewpoint at the location, estimate the height of the Roche Moutonnée.
2) Observe the Roche Moutonnée from the EarthCache coordinates. In which direction was the glacier travelling? Explain why you think this is the case.
3) Examine the Lee side of the Roche Moutonnée and describe any notable details that appear to prove this side was subjected to plucking.
4) OPTIONAL: Include in your log a photograph of you and/or your GPS device at the Earthcache coordinates (trying not to giveaway any of the answers to the questions).
Many thanks to the Leicestershire and Rutland Wildlife Trust for allowing me to place this EarthCache.