The Vale of Clwyd is a tract of low-lying ground in the county

County

A county is a jurisdiction of local government in certain modern nations. Historically in mainland Europe, the original French term, comté, and its equivalents in other languages denoted a jurisdiction under the sovereignty of a count A county is a jurisdiction of local government in certain...

 of Denbighshire

Denbighshire

Denbighshire is a county in north-east Wales. It is named after the historic county of Denbighshire, but has substantially different borders. Denbighshire has the distinction of being the oldest inhabited part of Wales. Pontnewydd Palaeolithic site has remains of Neanderthals from 225,000 years...

 in northeast Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

. The Vale extends south-southwestwards from the coast of the Irish Sea

Irish Sea

The Irish Sea separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel. Anglesey is the largest island within the Irish Sea, followed by the Isle of Man...

 for some 20 miles (about 30 km) forming a triangle of low ground bounded on its eastern side by the well-defined scarp

Escarpment

An escarpment is a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations.-Description and variants:...

 of the Clwydian Range

Clwydian Range

The Clwydian Range is a series of hills and mountains in north east Wales that runs from Llandegla in the south to Prestatyn in the north, with the highest point being the popular Moel Famau...

 and to the west by numerous low hills. The River Clwyd

River Clwyd

The River Clwyd is a river in North Wales which rises in the Clocaenog Forest northwest of Corwen.It flows due south until at Melin-y-Wig it veers northeastwards, tracking the A494 to Ruthin. Here it leaves the relatively narrow valley and enters a broad agricultural vale, the Vale of Clwyd...

 (Welsh: Afon Clwyd) which rises within Clocaenog Forest

Clocaenog Forest

Clocaenog Forest is in West Denbighshire/Conwy, Wales on Mynydd Hiraethog.It is 40 square miles in extent, mostly coniferous softwoods under the control of the Forestry Commission. It was planted in 1905 on what was mostly moorland and many hill farms. It is a highland region, mostly above 350...

, southwest of Denbigh, runs the full length of the vale. It is joined by the two major left bank tributaries of the River Clywedog

River Clywedog

The River Clywedog in the county borough of Wrexham, Wales has always been the lifeblood of the area, watering crops and livestock since early times, powering corn mills and driving industrial machinery...

 (Welsh: Afon Clywedog) and River Elwy

River Elwy

The River Elwy is a river in North Wales and is a tributary of the River Clwyd. The source of the river is sometimes said to be on the northern flank of Moel Seisiog, south-east of Llanrwst, at Ordnance Survey grid reference SH853593...

 (Welsh: Afon Elwy) and the smaller right bank tributary of the River Wheeler (Welsh: Afon Chwiler).

Settlement & Administration

At its seaward end are the coastal resorts of Kinmel Bay

Kinmel Bay

Kinmel Bay is a suburb of Rhyl in Conwy county borough, north-east Wales.According to the 2001 Census, together with neighbouring Towyn , it had a population of 7,864, of which 10.7% could speak Welsh....

 (Welsh: Bae Cinmel), Rhyl

Rhyl

Rhyl is a seaside resort town and community situated on the north east coast of Wales, in the county of Denbighshire , at the mouth of the River Clwyd . To the west is the suburb of Kinmel Bay, with the resort of Towyn further west, Prestatyn to the east and Rhuddlan to the south...

 and Prestatyn

Prestatyn

Prestatyn is a seaside resort, town and community in Denbighshire, North Wales. It is located on the Irish Sea coast, to the east of Rhyl. At the 2001 Census, Prestatyn had a population of 18,496.-Prehistory:...

 whilst the towns of Abergele

Abergele

Abergele is a community and old Roman trading town, situated on the north coast of Wales between the holiday resorts of Colwyn Bay and Rhyl, in Conwy County Borough. Its northern suburb of Pensarn lies on the Irish Sea coast and is known for its beach, where it is claimed by some that a ghost ship...

 and St Asaph

St Asaph

St Asaph is a town and community on the River Elwy in Denbighshire, Wales. In the 2001 Census it had a population of 3,491.The town of St Asaph is surrounded by countryside and views of the Vale of Clwyd. It is situated close to a number of busy coastal towns such as Rhyl, Prestatyn, Abergele,...

 (Welsh: Llanelwy) lie just inland. The other principal towns of the vale are Denbigh

Denbigh

Denbigh is a market town and community in Denbighshire, Wales. Before 1888, it was the county town of Denbighshire. Denbigh lies 8 miles to the north west of Ruthin and to the south of St Asaph. It is about 13 miles from the seaside resort of Rhyl. The town grew around the glove-making industry...

 (Welsh: Dinbych) and Ruthin

Ruthin

Ruthin is a community and the county town of Denbighshire in north Wales. Located around a hill in the southern part of the Vale of Clwyd - the older part of the town, the castle and Saint Peter's Square are located on top of the hill, while many newer parts of the town are on the floodplain of...

 (Welsh: Rhuthun). The area falls within the modern administrative county (and unitary authority

Unitary authority

A unitary authority is a type of local authority that has a single tier and is responsible for all local government functions within its area or performs additional functions which elsewhere in the relevant country are usually performed by national government or a higher level of sub-national...

) of Denbighshire

Denbighshire

Denbighshire is a county in north-east Wales. It is named after the historic county of Denbighshire, but has substantially different borders. Denbighshire has the distinction of being the oldest inhabited part of Wales. Pontnewydd Palaeolithic site has remains of Neanderthals from 225,000 years...

 and much of it lies within the Vale of Clwyd UK Parliamentary constituency

Vale of Clwyd (UK Parliament constituency)

The Vale of Clwyd is a constituency of the House of Commons of the Parliament of the United Kingdom. It elects one Member of Parliament by the first past the post system of election....

Geology

The Vale of Clwyd is a sedimentary basin

Sedimentary basin

The term sedimentary basin is used to refer to any geographical feature exhibiting subsidence and consequent infilling by sedimentation. As the sediments are buried, they are subjected to increasing pressure and begin the process of lithification...

 which takes the form of a half-graben

Graben

In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....

 whose eastern margin is marked by the Vale of Clwyd Fault. Like the Cheshire Basin

Cheshire Basin

The Cheshire Basin is a late Palaeozoic and Mesozoic sedimentary basin which extends under most of the county of Cheshire in northwest England. It extends northwards into the Manchester area and south into Shropshire...

 further to its east, it is mostly floored by thick deposits of Permian

Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

 and Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

. Around St Asaph, late Carboniferous

Carboniferous

The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

, Coal Measures

Coal Measures

The Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...

 mudstone

Mudstone

Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...

s and sandstones occur. The area was over-run by ice during the ice age

Ice age

An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

s whose legacy is a covering of glacial till across the area and a swarm of drumlins along the western edge of the vale. Alluvium

Alluvium

Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...

 is encountered across the floodplain

Floodplain

A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...

s of the River Clwyd and its tributaries.