button to main menu   Old Cumbria Gazetteer
placename:- Rocks - Sadgill to Wrengill
parish Longsleddale parish, once in Westmorland
county:- Cumbria
geological walk
10Km square:- NY40

specimen:- JandMN (406)

thumbnail BXO49, button to large image
Rock, hand specimen of a igneous rock, ignimbrite, from the track from Sadgill to Gatescarth Pass, Longsleddale, Westmorland, 2012.
Ordovician? Borrowdale volcanic group.
As the volcano erupted the lava fizzed at its mouth becoming more fluid, and the hot gassy 'pyroclastic flow' swept down from the vent. Molten lumps of lava in the ash were stretched out and flattened as the flow settled. The lighter lumps might be feldspar?
date:- 2012
period:- 2010s

specimen:- JandMN (407)

thumbnail BXO48, button to large image
Rock, hand specimen of a igneous rock, Andesite lava with vesicles, from the track from Sadgill to Gatescarth Pass, Longsleddale, Westmorland, 2012.
Ordovician? Borrowdale volcanic group.
The vesicles are gas bubbles which came out of solution in the lava when pressure reduced as it erupted from the volcano (like bubbles in lemonade).
date:- 2004
period:- 2000s

specimen:- JandMN (408)

thumbnail BXO50, button to large image
Rock, hand specimen of a igneous rock, Andesite lava with amygdales, infilled vesicles, from the track from Sadgill to Gatescarth Pass, Longsleddale, Westmorland, 2012.
Ordovician; Borrowdale volcanic group.
The vesicles are gas bubbles which came out of solution in the lava when pressure reduced as it erupted from the volcano. Later material permeated through the rock and desposited minerals in the holes, forming 'amygdales'.
date:- 2004
period:- 2000s

specimen:- JandMN (409)

thumbnail BXO51, button to large image
Rock, hand specimen of a slate metamorphosed from tuff, with spherulites, from the track from Sadgill to Gatescarth Pass, Longsleddale, Westmorland, 2012.
Ordovician; Borrowdale volcanic group.
The slate probably came from Wrengill Quarry.
date:- 2012
period:- 2010s

specimen:- JandMN (405)

thumbnail BXO47, button to large image
Rock, hand specimen of a metamorhic coarse sandstone, turbidite or greywacke, from the track from Sadgill to Gatescarth Pass, Longsleddale, Westmorland, 18 July 2004.
Ordovician?
Formed in an underwater avalanche or turbidity current.
date:- 2004
period:- 2000s

specimen:- JandMN (410)

thumbnail BXO52, button to large image
Rock, hand specimen of a quartz vein in volcanic tuff, from the track from Sadgill to Gatescarth Pass, Longsleddale, Westmorland, 2012.
Ordovician; Borrowdale volcanic group.
The quartz is probably associated with faulting.
date:- 2012
period:- 2010s

Clues to the Volcanoes
Walking up the track at the top of Longsleddale you are in an area of Borrowdale volcanic group rocks. The rocks you might see on the path provide clues to some of the volcanic activity.
NB: beware my amateur geological knowledge.

Old Cumbria Gazetteer - JandMN: 2013

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©  Martin and Jean Norgate: 2013
mailto button  email:- JandMN@norgate.freeserve.co.uk
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button, online connection  Geography Department, Portsmouth University