The Brook Stone Glacial Erratic (Frodsham) EarthCache
The Brook Stone Glacial Erratic (Frodsham)
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The Brook Stone in Frodsham is a glacial erratic. A glacial erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests. "Erratics" take their name from the Latin word errare (to wander, to roam, to ramble), and are carried by glacial ice, often over distances of hundreds of miles.
The Brook Stone is located on a plinth at the corner of Main Street and Marsh lane. It is very different to the natural stone in the Frodsham area that has been used to construct many of the surrounding buildings. Many years ago, guide books showed the stone as a Parish Boundary marker, it more recently being moved 400 metres east to its current position.
To claim a find of this earthcache, please e-mail me the answers to the following questions through my profile.
1. What are the Height, Width and Depth of the Brook Stone?
2. Estimate its volume, and with an average density of 2.7 g/cm3 (2700kg/m3), calculate its mass.
3. What Colour is the stone? What might give the stone this colour?
4. What type of rock is the Brook Stone, and is it Igneous, Sedimentary or Metamorphic?
5. Based on the images below, is it Fine, Medium or coarse grained?
6. Identify the local rock type in the Frodsham area. (hint : Frodsham is the start of a 34 mile trail heading south to Whitchurch)
7. Briefly explain how both the erratic and local stone around Frodsham were formed.
8. Optionally, upload a photo of yourself and/or GPS with the Brook Stone.
Additional Hints
(No hints available.)