The Flintshire Coalfield in north-east 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...

 is one of the smaller British

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 coalfields. It extends from the Point of Ayr

Point of Ayr

Point of Ayr is the northernmost point of mainland Wales. It is situated immediately to the north of Talacre in Flintshire, at the mouth of the Dee estuary. It is to the southwest of the Liverpool Bay area of the Irish Sea...

 in the north, along the Dee Estuary

Dee Estuary

The Dee Estuary is a large estuary by means of which the River Dee flows into Liverpool Bay. The estuary starts near Shotton after a five miles 'canalised' section and the river soon swells to be several miles wide forming the boundary between the Wirral Peninsula in north-west England and...

 through Connah's Quay

Connah's Quay

Connah's Quay is the largest town in Flintshire, North Wales, lying on the River Dee, near the border with England. It can be accessed by road from the A550, by rail from the nearby Shotton station and also lies on the National Cycle Network Route 5. It is situated near the region's industrial...

 to Caergwrle

Caergwrle

Caergwrle is a village in the county of Flintshire, in north east Wales. Approximately 5–6 miles from Wrexham and situated on the A541 road, it is contiguous with the village of Abermorddu and closely related to the village of Hope . The village lies on the River Alyn and sits at the base of Hope...

 in the south. A small part extends onto the Wirral

Wirral Peninsula

Wirral or the Wirral is a peninsula in North West England. It is bounded by three bodies of water: to the west by the River Dee, forming a boundary with Wales, to the east by the River Mersey and to the north by the Irish Sea. Both terms "Wirral" and "the Wirral" are used locally , although the...

 i.e. English

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 coast of the estuary at Neston which was the site of a coalmine for a period. The coal-bearing strata

Stratum

In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...

 continue southwards of Caergwrle as the Denbighshire Coalfield

Denbighshire Coalfield

The Denbighshire Coalfield in north-east Wales is one of the smaller British coalfields. It extends from near Caergwrle in the north, southwards through Wrexham, Ruabon and Rhosllanerchrugog to Chirk in the south. A small part extends into Shropshire around Oswestry...

. Together the two coalfields are known as the North Wales Coalfield.

Several coal seams are named in the sequence. Some seams are absent in the northern part of the coalfield and are labelled as (S) whilst the others occur across the coalfield as a whole. The Chwarelau Seam which appears only in the north actually occurs within the underlying Millstone Grit

Millstone Grit

Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills...

 sequence rather than the 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...

proper. The seams are listed stratigraphically with the uppermost (youngest) at the head of the list and the lowermost (oldest) at the foot. Local names are shown in brackets.

Within the Pennine Middle Coal Measures Formation:

• Upper Main (S)
• Pontybodkin Mountain (S)
• Tryddyn Half-Yard (S)
• Drowsell
• Powell
• Hollin (Cannel)
• Crank (Three Quarter)(S)
• Quaker (S)
• Black Bed
• Main (Five Yard)
• Lower Bench (Three Yard)
• Crown (Mostyn Two Yard)

Within the Pennine Lower Coal Measures Formation:

• Upper Red (Durdog)
• Lower Red (Yard)
• Cannel (Stone)
• Stone (divides into Wall and Bench in south)(Hard Five Quarter)
• Nant (Badger)
• Ruabon Yard (Soft Five Quarter)
• Premier (Bychton Two Yard)
• Llwyneinion Half Yard (Picton Three Quarter)

Within the Gwespyr Sandstone Formation of the Millstone Grit Group:

• Chwarelau (N) (Little Coal)