Violent Vulcanism in England - the Pavey Ark Breccia

Near the summit of Pavey Ark, Lake District National Park, England.

The rocks in this photo belong to the Pavey Ark Member (formerly the 'Pavey Ark Breccia') in the Borrowdale Volcanic Group (Ordovician). This is a very coarse tuff with many angular rock fragments, volcanic bombs and andesite lava spatter, possibly resulting from a pyroclastic flow settling into water; the whole lot subsequently disrupted by slumping and mass movement (Millward et al, 2000). This is indicative of the very violent volcanic activity which took place here way back in the Ordovician.

Reference:
Millward, D. et al. 2000. Geology of the Ambleside district, British Geological Survey Memoir for 1:50000 Geological Sheet 38, London HMSO.