Some rock formations that are located 2000ft above sea level, on the north rake of Pavey Ark, show where small volcanic ballistic projectiles had fallen and settled in an ancient ocean where an arc of volcanic islands once existed.
Subaqueous Fallout Formations
Pyroclastic fallout consists of particles that have been ejected from volcanic vents and have travelled through the atmosphere before falling to earth or into water. Pyroclastic material greater than 64mm in diameter are known as volcanic bombs when molten, or volcanic blocks when solid. Particles in the range of 2 to 64mm in diameter are known as Lapilli, and particles less than 2mm in diameter are referred to as volcanic ash. Lapilli (Latin for “little stones”) are spheroid, teardrop, dumbbell or button-shaped droplets of molten or semi-molten lava, which are ejected from a volcanic eruption and then fall to earth while still at least partially molten. Pyroclastic material that falls on land is “subaerial fallout” and that falling into water is “subaqueous fallout”.
Pavey Ark over Stickle Tarn
Facing south-east over Stickle Tarn, the cliff face of Pavey Ark is a little over 1⁄4 mile (400 metres) across and 120 metres in height. Exposed rocks near the summit tell a story of ancient volcanic activity. The rocks here were formed by a chain of island arc volcanoes in the ancient Iapetus Ocean, around 460 million years ago. This is indicative of the very violent volcanic activity which took place here way back in the Middle Ordovician Period. When active, the volcanoes’ explosive nature produced pyroclastic lava flows that settled into the ocean. Close inspection of the rock surfaces reveals many angular fragments, volcanic bombs and andesitic lava spatter. The Iapetus Ocean gradually disappeared as its floor was pulled beneath the converging Laurentia, Baltica and Avalon continental masses.
The tectonic plates of Laurentia, Baltica and Avalonia
“Laurentia collides with the Grampian volcanic Arc causing the first stage of Caledonian mountain building, from 475 – 465 million years ago. Laurentia and Baltica both rotate anticlockwise as their tectonic plates move. Iapetus Ocean begins to close. England-Wales and southern Ireland, part of Avolonia micro-continent, arrive in the neighbourhood, heading north (blue arrow). Note that all the action takes place south of the Equator.”
Brian Ricketts, Geological Digressions
Just for a bit of fun, my wife and I decided to name the rock “Pavia’s Rock”. It’s believed that the name Pavey comes from a 13th century female name of “Pavia”, who had a milking shed (ark) in Mill Gill (now Stickle Ghyll). However, there are a few theories behind the name. One is that it’s named after a sheiling that was located high on the Langdale Pikes. Another is the “ark” refers to a large chest to store grains in, which links with the corn mill that was located at Millbeck Farm (not to be confused with the fulling mill near the present day Stickle Barn). I prefer the milking shed theory because of the fact there was an influx of foreign farm workers in the 13th century that settled in the valley of Great Langdale. One thing is certain, the “ark” in the name Pavey Ark doesn’t refer to an arc of volcanoes; that is simply a coincidence.
Pavey Ark and the North Rake on the right
Easy Gully is the dominant cleft which dissects the rising ridge of the North Rake. The first crag at the base of the ridge is Pavia’s Rock.
Pavia’s Rock from where Bright Beck enters Stickle Tarn
The summit outcrop of Pavia’s Rock
Subaqueous Fallout Formations (1)
Subaqueous Fallout Formations (2)
Jaclyn admiring one of Pavia’s volcanic bombs!
Subaqueous Fallout Formations (3)
Subaqueous Fallout Formations (4)
Subaqueous Fallout Formations (5)
Subaqueous Fallout Formations (6)
The largest ring, and on the summit of the outcrop.
Pavey Ark’s North Rake from the summit of Pavia’s Rock
Frankie relaxing with Harrison Stickle and Pavey Ark behind him
The narrow cleft of Jack’s Rake, a popular grade 1 scramble, can be seen centre rising from the base of the cliff face.
Jaclyn admiring the cliff face of Pavey Ark
Thanks, sources and further reading:
Brian Ricketts of Geological Digressions