Dalby Group

Last updated
Dalby Group
Stratigraphic range: Wenlock epoch of Silurian
Type Group
Sub-unitsNiarbyl Formation
Overlies Manx Group (probably unconformably)
Thicknessc.1200m
Lithology
Primary sandstone
Other siltstone, mudstone
Location
Region Isle of Man
CountryUnited Kingdom (Crown dependency)
Extent Niarbyl to Peel
Type section
Named for Dalby

The Dalby Group is a Silurian lithostratigraphic group (a sequence of rock strata) on the west coast of the Isle of Man in the Irish Sea. The name is derived from the village of Dalby near the west coast of the island. Together with those of the adjoining Manx Group, the rocks of the Group have also previously been referred to as the Manx Slates or Manx Slate Series. The group comprises wacke sandstones with siltstones and mudstones which reach a thickness of about 1200m in the west of the island. It contains only the single Niarbyl Formation which is exposed along the coast between Niarbyl Point and the town of Peel to the north. [1] [2] [3]

Related Research Articles

Geography of the Isle of Man

The Isle of Man is an island in the Irish Sea, between Great Britain and Ireland in Western Europe, with a population of almost 85,000. It is a British Crown dependency. It has a small islet, the Calf of Man, to its south. It is located at 54°15′N4°30′W.

Old Red Sandstone Assemblage of rocks in the North Atlantic region

The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also extends northwards into Greenland and Svalbard. These areas were a part of the ancient continent of Euramerica/Laurussia. In Britain it is a lithostratigraphic unit to which stratigraphers accord supergroup status and which is of considerable importance to early paleontology. For convenience the short version of the term, ORS is often used in literature on the subject. The term was coined to distinguish the sequence from the younger New Red Sandstone which also occurs widely throughout Britain.

The Lias Group or Lias is a lithostratigraphic unit found in a large area of western Europe, including the British Isles, the North Sea, the Low Countries and the north of Germany. It consists of marine limestones, shales, marls and clays.

Niarbyl, Isle of Man

Niarbyl, which means "the tail" in Manx for the way it extends into the Irish Sea, is a rocky promontory on the southwest coast of Isle of Man between Port Erin and Peel. It is best known for its spectacular sea views which include the Calf of Man and, on clear days, the mountains of Ireland.

Iapetus Suture One of several major geological faults caused by the collision of several ancient land masses forming a suture

The Iapetus Suture is one of several major geological faults caused by the collision of several ancient land masses forming a suture. It represents in part the remains of what was once the Iapetus Ocean. Iapetus was the father of Atlas in Greek mythology, making his an appropriate name for what used to be called the 'Proto-Atlantic Ocean'. When the Atlantic Ocean opened, in the Cretaceous period, it took a slightly different line from that of the Iapetus suture, with some originally Laurentian rocks being left behind in north-west Europe and other, Avalonian, rocks remaining as part of Newfoundland.

The Mercia Mudstone Group is an early Triassic lithostratigraphic group which is widespread in Britain, especially in the English Midlands – the name is derived from the ancient kingdom of Mercia which corresponds to that area. It is frequently encountered in older literature as the Keuper Marl or Keuper Marl Series.

Eday Group

The Eday Group is a Devonian lithostratigraphic group in Orkney, northern Scotland. The name is derived from the island of Eday where the strata are exposed in coastal cliffs.

Sherwood Sandstone Group

The Sherwood Sandstone Group is a Triassic lithostratigraphic group which is widespread in Britain, especially in the English Midlands. The name is derived from Sherwood Forest in Nottinghamshire which is underlain by rocks of this age. It has economic importance as the reservoir of the Morecambe Bay gas field, the second largest gas field in the UK.

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 Albion Glacigenic Group is a Quaternary lithostratigraphic group present in those parts of Great Britain which lie north of the southern limit of Anglian glaciation, but south of the Devensian glacial limit, and also includes deposits in the Isle of Man and offshore areas. It consists of a wide range of unconsolidated superficial deposits including till, sands, gravels, silts and clay of glacial, glaciofluvial, glaciolacustrine and glaciomarine origin. Its upper boundary is the present day ground surface or unconformable contact with units of the Caledonia Glacigenic Group, the Britannia Catchments Group or the British Coastal Deposits Group. It was previously known as the South Britain Glacigenic Group or Older Drift

The Caledonia Glacigenic Group is a Quaternary lithostratigraphic group present across the whole of Great Britain to the north and west of the furthest limit of Devensian glaciation i.e. throughout Scotland, Wales and northern England. It consists of a wide range of deposits deriving from the Devensian glaciation of glacial, glaciofluvial, glaciolacustrine and glaciomarine origin. It was previously known as the South Britain Glacigenic Group. Its upper boundary is the present day ground surface or an unconformable contact with the Britannia Catchments Group or the British Coastal Deposits Group.

The geology of the Isle of Man consists primarily of a thick pile of sedimentary rocks dating from the Ordovician period, together with smaller areas of later sedimentary and extrusive igneous strata. The older strata was folded and faulted during the Caledonian and Acadian orogenies The bedrock is overlain by a range of glacial and post-glacial deposits. Igneous intrusions in the form of dykes and plutons are common, some associated with mineralisation which spawned a minor metal mining industry.

The Kendal Group is a Silurian lithostratigraphic group in the southern Lake District and the Howgill Fells of northern England. The name is derived from the town of Kendal in Cumbria. The Group is included within the Windermere Supergroup. The group comprises couplets of siltstone and mudstone along with some turbiditic sandstones and which may exceed a thickness of 4200m. Its lower unit is the Bannisdale Formation above which is the Kirkby Moor Formation. Some of the rocks of the latter were earlier included in the Underbarrow and Scout Hill Flag formations.

Coniston Group

The Coniston Group is a Silurian lithostratigraphic group in the southern Lake District and north-west Pennines of northern England. The name is derived from the small town of Coniston in Cumbria. The rocks of the Group have also previously been referred to as the Coniston Grits or Coniston Grits Formation and Coniston Subgroup. The group comprises sandstones and siltstones and some laminated hemipelagites which achieve a thickness of between 1400 and 1900m. Overlain by the Bannisdale Formation of the Kendal Group and underlain by the Wray Castle Formation of the Tranearth Group, it is divided into several formations. These are, in ascending order : Wray Castle, Gawthwaite, Latrigg, Poolscar, Moorhow and Yewbank.

The Tranearth Group is a Silurian lithostratigraphic group in the southern Lake District and Howgill Fells of the Pennines of northern England. The name is derived from the locality of Tranearth near Torver in Cumbria. The Group is included within the Windermere Supergroup. It comprises laminated hemipelagites and siltstones and some sandstones and limestone which achieve a thickness of between 500 and 1000m. It is divided into a lower Brathay Formation which is overlain by the Birk Riggs Formation and then by an upper Coldwell Formation.

The Manx Group is an Ordovician lithostratigraphic group in the Isle of Man in the Irish Sea. The name is derived from the name of the island which is largely formed from them; these rocks have also previously been referred to as the Manx Slates or Manx Slates Series. The group comprises dark mudstones with siltstone laminae and some sandstones and which exceed a thickness of 3000m. It is divided into a lowermost Glen Dhoo Formation which is overlain by the Lonan, Mull Hill, Creg Agneash and Maughold formations in ascending order. A fault separates these from the overlying Barrule, Injebreck, Glen Rushen and Creggan Mooar formations which are in turn separated by a fault from an overlying Ladyport Formation.

The geology of Exmoor National Park in south-west England contributes significantly to the character of a landscape which was designated as a national park in 1954. The bedrock of the area consists almost wholly of a suite of sedimentary rocks deposited during the Devonian, a period named for the English county of Devon in which the western half of the park sits. The eastern part lies within Somerset and it is within this part of the park that limited outcrops of Triassic and Jurassic age rocks are to be found.

Holy Island Group Cambro-Ordovician geologic formation in Wales

The Holy Island Group is a sequence of metasedimentary rocks of Cambro-Ordovician age found in northern and western Anglesey and the adjacent Holy Island in North Wales. It comprises four formations; a lower South Stack Formation, an overlying Holyhead Formation, a succeeding Rhoscolyn Formation and an uppermost New Harbour Formation. The South Stack Formation outcrops on Holy Island, between Holyhead and South Stack and at Rhoscolyn, and also inland on Anglesey itself between Mynydd Mechell and Carreglefn. The Holyhead and Rhoscolyn formations are restricted to the Holyhead Mountain and Rhoscolyn areas of Holy Island. The New Harbour Formation, which previously enjoyed 'Group' status, is some 2km thick and conformably overlies the Rhoscolyn Formation. It extends across much of northern and western Anglesey and Holy Island.

References

  1. "Dalby Group". The BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved January 20, 2019.
  2. "Niarbyl Formation". The BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved January 20, 2019.
  3. Isle of Man solid and drift geology, 1:50,000 scale. British Geological Survey, NERC. 2001. ISBN   0751833266.