This is one of a series of EarthCaches placed at sites within the Westmorland Dales area which the Cumbria GeoConservation group considers as being good examples of various aspects of the local geology. Our local geological research has been made possible by the Westmorland Dales Landscape Partnership Scheme, jointly led by the Friends of the Lake District and the Yorkshire Dales National Park Authority and has been grant funded by the National Lottery Heritage Fund.
The origin and even the correct pronunciation of the name of this stone circle, between Orton and Raisbeck, are not clear. Is it Game-lands, or Gamel-lands? It could be named after an early landowner (Gamel’s lands) or the name could come from ‘gamall’ which in old Norse translates as ‘old’. There is little doubt that the circle is old. It was probably constructed between 4 and 5 thousand years ago, in the late Neolithic or Early Bronze Age. Circles like this are thought to have been used for gatherings and rituals and may have had links to the seasonal cycles. Like other similar monuments, the stones do not form a perfect circle and there are some gaps. The stones here were originally standing upright, set in a bank, but over the years, they have fallen and the bank has been flattened. In the 1860s, some of the stones were ‘blown up’ to make the field in which they stand easier to plough. So what you see now is probably much less impressive than the original circle.
The majority of the stones in the circle, like the one nearest the kissing gate, are boulders of Shap granite. The exposure of the granite lies about 8 km NW of here. You can see the Shap Granite Quarry from the circle on a fine day. However, it is most unlikely that people moved the stones cross country from the exposure; it is much more likely that the stones were moved eastwards by glaciers during the most recent Ice Age, and left scattered around the landscape when the ice melted about 11 thousand years ago. So they could have been collected from a relatively local area to build the circle.
Shap granite is a very distinctive rock, characterised by large pink feldspar crystals set in a matrix of smaller crystals of grey glassy quartz and white feldspar, with speckles of black biotite. The stones in the circle have been weathered, probably before they were picked up by the ice, as well as during their transport, and in the 11 thousand or so years after the ice melted, so the details of the crystal structure are not always easy to see.
Granite is an igneous rock, that is, one that has solidified from a molten magma. In the case of granite, this happens as the magma cools at a depth of several kilometres below the Earth’s surface. Once most of the magma has solidified, with the various ions in the melt fitting into the growing crystals, there are inevitably some ions, and also some water, left over in pockets in the rock – a bit like the squidgy middle of a chocolate brownie, though not formed in the same way. As the granite cools further, it contracts and cracks. If a crack reaches the surface, the water escapes as steam, and the remaining ions quickly form very tiny crystals in the crack. Typically, these crystals are darker than the main body of the granite, forming a dark vein, called an aplite vein, in the granite. If the crack does not reach the surface, the water remains with the ions in the crack and over time, much larger, usually pale crystals grow. This type of pale vein in the granite is called a pegmatite vein.
Permission to set this EarthCache has been kindly given by the landowner, Mr M Mawson.
Questions:
To claim this EarthCache, please send your answers in a message, either by e-mail or through the Message Centre. Do not put them in your log. You do not have to wait for a reply before logging; if there is a problem with your answers we will let you know. Pictures of your visit are very welcome in your log, but please avoid giving away any of the answers.
1. Describe the general appearance of the large Shap granite boulders. Describe, including the shape and colour, the crystal type that is the most resistant to being broken down by weathering. (Hint: this type of crystal will be sticking up above the general surface of the rock)
2. In the 1860s, some of the Shap granite boulders are reported to have been ‘blown up’. This would have left smaller pieces with sharp edges. Do some of the smaller boulders still have sharp edges, or have these been weathered to a smoother shape over the last 160 or so years?
3. One of the granite boulders, towards the north-west part of the circle, has veins in it. Describe these veins and state whether they would be called aplite or pegmatite veins.
4. Walk round the circle and find the one large boulder in the circle that is not Shap granite. Describe that boulder, explaining in particular how it differs from the granite.