Skiddaw Group

Last updated
Skiddaw Group
Stratigraphic range: Late Cambrian-Mid-Ordovician
Path up Skiddaw from Carl Side - geograph.org.uk - 393490.jpg
Slates of the Kirk Stile Formation, exposed just below Skiddaw summit ridge
Type Group
Sub-unitsBitter Beck, Watch Hill, Hope Beck, Loweswater, Kirk Stile, Catterpallot, Buttermere, Tarn Moor, Murton & Kirkland Formations
Underlies Borrowdale Volcanic Group, Eycott Volcanic Group
Overliesnot observed
Thickness~5,000 m (16,000 ft)
Lithology
Primary Mudstone
Other Siltstone, sandstone
Location
Coordinates 54°42′N3°06′W / 54.7°N 3.1°W / 54.7; -3.1 Coordinates: 54°42′N3°06′W / 54.7°N 3.1°W / 54.7; -3.1
Approximate paleocoordinates 61°30′S16°06′W / 61.5°S 16.1°W / -61.5; -16.1
Region Cumbria
Country England
Flag of the United Kingdom.svg  United Kingdom
Extentnorthern Lake District, Black Combe & Cross Fell
Type section
Named for Skiddaw

For the Skiddaw group of hills, see Skiddaw Group

The Skiddaw Group is a group of sedimentary rock formations named after the mountain Skiddaw in the English Lake District. The rocks are almost wholly Ordovician in age (Tremadoc through Arenig to Llanvirn epochs) though the lowermost beds are possibly of Cambrian age. [1] This rock sequence has previously been known as the Skiddaw Slates, the Skiddaw Slates Group and the Skiddavian Series. Its base is not exposed but in its main outcrop area, it is considered to be in excess of 5,000 metres (16,000 ft) thick though less elsewhere. [2] It consists largely of mudstones and siltstones with subordinate wacke-type sandstones. Their main occurrence is within the northern and central fells of the Lake District, either side of the major ENE-WSW aligned Causey Pike Fault, but inliers are found at Black Combe in the south of the Lake District and at Cross Fell in the North Pennines.

Contents

Stratigraphy

In the Northern Fells of the Lake District, the Skiddaw Group comprises five formations of which the earliest/lowest is the Bitter Beck Formation. This is succeeded by the Watch Hill Formation, then the Hope Beck, Loweswater and Kirk Stile Formations in ascending order. The inlier at Cross Fell comprises just the Catterpallot Formation, a wacke sandstone which is the rough equivalent of the Watch Hill Formation, itself a wacke sandstone as is the Loweswater Formation.

Within the Central Fells are the Buttermere Formation and the overlying Tarn Moor Formation. These are matched by the Murton Formation (grey slates and thin sandstones) and the Kirkland Formation (mudstones with tuffs and lavas) at Cross Fell. The Buttermere Formation is interpreted as an olistostrome. The Tarn Moor and Kirkland Formations contain some volcaniclastic rocks. The inlier to the south at Black Combe contains the wackes of the Knott Hill Formation.

The group underlies the Borrowdale Volcanic Group in the southern and central Lake District and the Eycott Volcanic Group in the northern part of the district. [3]

The Kirkland Formation has provided fossils of Dichograptus octobrachiatus and Heminectere rushtoni . [4]

Metamorphism

The sequence was affected by low-grade regional metamorphism and deformation associated with the Acadian Orogeny, causing the dominant fine-grained parts of the sequence to become slates. The resulting slaty cleavage is parallel to the axial plane of regional folds. [5]

Related Research Articles

Dale Head

Dale Head is a fell in the north-western sector of the Lake District, in northern England. It is 753 metres or 2,470 feet above sea level and stands immediately north of Honister Pass, the road between Borrowdale and Buttermere.

Clough Head

Clough Head is a fell, or hill, in the English Lake District. It marks the northern end of the main ridge of the Helvellyn range and is often walked as part of the ridge walk. The fell stands south of the village of Threlkeld and the A66 road, and it forms the steep eastern side of the tranquil valley of St John's in the Vale.

Crag Hill

Crag Hill is a mountain in the North Western part of the English Lake District. It was formerly known as Eel Crag; however, the Ordnance Survey now marks Eel Crag as referring to the northern crags of the fell. It is not to be confused with another Crag Hill lying on the border of North Yorkshire.

High Stile

High Stile is a mountain in the western part of the Lake District in North West England. It is the eleventh-highest English Marilyn, standing 807 metres (2,648 ft) high, and has a relative height of 362 metres (1,187 ft).

Red Screes

Red Screes is a fell in the English Lake District, situated between the villages of Patterdale and Ambleside. It may be considered an outlier of the Fairfield group in the Eastern Fells, but is separated from its neighbours by low cols. This gives Red Screes an independence which is reflected in its prominence.

Black Combe

Black Combe is a fell in the south-west corner of the Lake District National Park, England, just 4 miles (6.4 km) from the Irish Sea. It lies near the west coast of Cumbria in the borough of Copeland and more specifically, in the ancient district of Millom. It is 1,970 ft (600 m) high and stands in isolation, some 10 mi (16 km) away from any higher ground; this factor offers an excellent all-round panoramic view of land and sea, weather permitting.

Mellbreak

Mellbreak is a hill in the Western part of the English Lake District. Despite being surrounded on all sides by higher fells, it stands in isolation. It is surrounded on three sides by a "moat" of deep marshy land, and on the east side by the lake of Crummock Water. The fell forms a partnership with the lake, running parallel to it, falling sheer into it, and regularly providing the backdrop for pictures of it.

Gowbarrow Fell

Gowbarrow Fell is a low fell in the English Lake District. It is an outlier of the Eastern Fells, standing to the north of Ullswater, bounded on one side by Aira Beck with its waterfall Aira Force. The waterfall is a popular attraction for visitors to the area.

Hopegill Head

Hopegill Head is a fell in the English Lake District in Cumbria. It is located nine kilometres west of the town of Keswick and is well seen from the B5292 road which crosses the Whinlatter Pass.

Wandope

Wandope is a fell in the north-western area of the English Lake District. It lies to the east of Crummock Water and south of Crag Hill. From the summit there are excellent panoramas of the Sca Fell and High Stile ranges.

Whiteless Pike

Whiteless Pike is a fell in the north-western English Lake District. It stands immediately east of Crummock Water and forms a pyramid shape when viewed from Rannerdale. In his celebrated guide to the Lakeland fells, Alfred Wainwright called it "the Weisshorn of Buttermere". There are good views of Great Gable and the Scafells from the summit.

Sail (Lake District)

Sail is a hill in the English Lake District, lying between Derwentwater and Crummock Water.

Hen Comb

Hen Comb is a fell in the west of the English Lake District. One of the Loweswater Fells it lies to the south of Loweswater lake and Loweswater village. Although of only moderate height, its ascent can be difficult as it is largely surrounded by bogs.

Gavel Fell

Gavel Fell is a hill in the English Lake District. Centremost of the five Loweswater Fells in the western part of the District, it stands between Hen Comb and Blake Fell. Of moderate altitude it can be climbed from Loweswater village, or from Croasdale to the west.

The geology of County Durham in northeast England consists of a basement of Lower Palaeozoic rocks overlain by a varying thickness of Carboniferous and Permo-Triassic sedimentary rocks which dip generally eastwards towards the North Sea. These have been intruded by a pluton, sills and dykes at various times from the Devonian Period to the Palaeogene. The whole is overlain by a suite of unconsolidated deposits of Quaternary age arising from glaciation and from other processes operating during the post-glacial period to the present. The geological interest of the west of the county was recognised by the designation in 2003 of the North Pennines Area of Outstanding Natural Beauty as a European Geopark.

Dent Group

The Dent Group is a group of Upper Ordovician sedimentary and volcanic rocks in north-west England. It is the lowermost part of the Windermere Supergroup, which was deposited in the foreland basin formed during the collision between Laurentia and Avalonia. It lies unconformably on the Borrowdale Volcanic Group. This unit was previously known as the Coniston Limestone Group or Coniston Limestone Formation and should not be confused with the significantly younger Coniston Group.

Exmoor Group

The Exmoor Group is a late Devonian to early Carboniferous lithostratigraphic group in southwest England whose outcrop extends from Croyde in north Devon east across Exmoor to Minehead in west Somerset. The group comprises the following formations the:

The Eycott Volcanic Group is a group of volcanic rock formations of Ordovician age named after the locality of Eycott Hill in the English Lake District. The group overlies the Skiddaw Group and is unconformably overlain by a variety of different Devonian and Carboniferous age rocks.

Causey Pike Fault Major fault zone in the English Lake District

The Causey Pike Fault or Causey Pike Thrust is a major WSW-ENE trending fault within the Lower Paleozoic rocks of the English Lake District. It is named for Causey Pike, where the fault was first recognised.

Geology of the Lake District

The geology of England's Lake District is dominated by sedimentary and volcanic rocks of mainly Ordovician age underpinned by large granitic intrusions. Younger sedimentary sequences outcrop on the edges of the Lake District area, with Silurian to the south, Carboniferous to the north, east and west and Permo-Triassic to the west and east. The entire area was covered by a Mesozoic sequence that was eroded off during Paleogene uplift related to the opening of the North Atlantic. During the Quaternary the area was affected by repeated glaciations, which sculpted the current mountainous landscape.

References

  1. British Geological Survey 1999 Keswick England and Wales sheet 29 Solid 1:50,000 Keyworth, Nottingham, BGS
  2. British Geological Survey. "Skiddaw Group". BGS Lexicon of Named Rock Units. Retrieved 21 October 2019.
  3. Stone et al 2010 British Regional Geology. Northern England (5th edn) Keyworth, Nottingham. British Geological Survey
  4. Randel Crag, Skiddaw at Fossilworks.org
  5. Stone P., Cooper A.H. & Evans J.A. (1999). "The Skiddaw Group (English Lake District) reviewed: early Palaeozoic sedimentation and tectonism at the northern margin of Avalonia". Geological Society, London, Special Publications. 160: 325–336. doi:10.1144/GSL.SP.1999.160.01.21.

Further reading