Old Cumbria Gazetteer - ford, Threlkeld


included in:-	geological walk, Blease Fell
	ford, Threlkeld
site name:-	Blease Fell
civil parish:-	Threlkeld (formerly Cumberland)
county:-	Cumbria
locality type:-	geological site
locality type:-	river
locality type:-	ford
locality type:-	waterfall
coordinates:-	NY29982699
1Km square:-	NY2926
10Km square:-	NY22

	BPR25.jpg The ford on the path up the Glenderaterra valley. (taken 26.9.2008) BPR27.jpg Chiastolite in the Skiddaw Group mudstone. (taken 26.9.2008)
	The unnamed stream exposes Skiddaw Group mudstones which have been slightly metamorphosed by contact with the Skiddaw granite intrusion to the north. One of the indicators is the presence of chiastolite in the rock. This was low grade metamorphism; raised temperature, but not pressure - notice that the crystals lie in all directions, not aligned by pressure.
	Chiastolite is aluminium silicate, a variety of andalusite. The crystals are flat plates up to 4cm square, usually with a black spot in the middle.
	The rock is very broken up, and stained by iron.
	NB: beware my amateur geological knowledge.

	JandMN : 389 BXO30.jpg Rock, hand specimen of Skiddaw mudstone, moderately metamorphosed to slate with crystals of chiastolite, from a streambed on Blease Fell, Threlkeld, Cumberland, NY29972698, 12 October 2012. Skiddaw group, mudstone; Ordovician, Llanvirn/Arenig. Chiastolite is a variety of andalusite, aluminium silicate, Al2SiO5. (taken 12.10.2012)

	BPR28.jpg Chiastolite in the Skiddaw Group mudstone. (taken 26.9.2008) BPQ19.jpg Chiastolite in the Skiddaw Group mudstone. (taken 24.8.2008) BPR26.jpg Waterfall above the ford. (taken 26.9.2008) BXM60.jpg (taken 12.10.2012)

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