The coordinates take you to the centre of the Claewen dam. There is limited parking at either end of the dam (yes, you are allowed to drive across the top of the dam) and a larger carpark with toilet facilities at the base of the dam. The Claerwen valley is a glacial (and very beautiful) valley. It is wide (although varying in width), U shaped, and much larger than a river could erode. The Claerwen dam itself is a Gravity Dam, where the weight of the dam is sufficient to hold back the horizontal force of the water.
When you stand at the coordinates, have a look around you and consider why the Claerwen dam was placed where it was. Why for instance is it immediately above the Afon Arban joining the Claerwen. So to log this earthcache, I need you to answer the following questions:
1. Is the valley comparatively narrow or wide at the place of the dam? Why does the valley vary in width?
2. How do these answers relate to the bedrock- obviously the dam needs to be connected to bedrock to be structurally sound. Is it more or less obvious at the dam than 200 metres above or below the dam? Would you expect it to be harder at the dam than above or below the dam?
3. The Afon Arban does not flow into the Claerwen reservoir. Why doesn't this matter? You will have passed the answer to this on you passage up the valley.
4. To prove you have visited the dam look at the nearby plaque and tell me Alderman Boughton's two given (christian) names.
You may log this earthcache at the same time as telling me the answers to the above questions but please do not include answers in your log. Logs that include answers will be deleted. Photos are welcome-it's a beautiful place- but not required. When you visit another reservoir in the future,perhaps you could look at it in the context of the surrounding countryside.