Carreg yr Imbill is the remains of a large

dolerite Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained ...

with pegmatite pods and

quarry A quarry is a type of open-pit mining, open-pit mine in which dimension stone, rock (geology), rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some juri ...

Pwllheli Pwllheli () is a market town and community of the Llŷn Peninsula ( cy, Penrhyn Llŷn) in Gwynedd, north-western Wales. It had a population of 4,076 in 2011 of whom a large proportion, 81%, are Welsh speaking. Pwllheli is the place where Plaid ...

Gwynedd Gwynedd (; ) is a Local government in Wales#Principal areas, county and preserved county (latter with differing boundaries; includes the Isle of Anglesey) in the North West Wales, north-west of Wales. It shares borders with Powys, Conwy County B ...

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

. The dolerite was mined by the

Liverpool and Pwllheli Granite Company Liverpool is a City status in the United Kingdom, city and metropolitan borough in Merseyside, England. With a population of in 2019, it is the List of English districts by population, 10th largest English district by population and its E ...

(sometimes known as the Pwllheli Granite Company), which used the diorite for stone setts to pave the streets. The worked out quarry forms the basis for a large holiday village which is run by the Haulfryn Group, the same company which runs The Warren in Abersoch.

References

Pwllheli Quarries in Gwynedd Rock formations of Gwynedd {{Gwynedd-geo-stub