North Yorkshire Geodiversity Partnership

Ingleton Quarry, Precambrian
Malham Cove Carboniferous
West Burton Falls Carboniferous
Cleave Dyke Quarry, Jurassic


Geological Sites

Geological Sites

Rocks for us

Rocks For Us

Carboniferous – Tropical Swamps and Deltas

The oldest rocks in the area are found in the core of the Harrogate anticline (Craven Group) and in the north-west. By 330 million years ago mud and sand, from huge river deltas, was periodically being washed into a tropical sea. Over millions of years changes in sea level produced repeated cycles (cyclothems) of alternating beds of limestones, mudstones, sandstones and coals (the Yoredale Group).


Photo: Howe Quarry, Harrogate, well-bedded Harrogate Roadstone limestone of the Craven Group © BGS (NERC)


Photo: Ever Bank – Old quarry on Ever Bank, Middleham, exposing the Richmond Chert Member of the Yoredale Group © BGS (NERC)

As time progressed, the extent of the river delta systems became greater and thick beds of sandstones and mudstones (the Millstone Grit Group) were laid down. North west of Ripon in the Winksley area there are small outcrops of Pennine Coal Measures Group sandstones with thin coals. The rocks were then subjected to erosion, and during the Variscan mountain building event, were faulted, folded and injected with mineral veins.


Photo: Plompton Rocks, Harrogate, weathered Upper Plompton Grit. © BGS (NERC)

Map: The bedrock geology of the Vale of York Project Area

QUATERNARY Holocene Glacial and post glacial deposits Regional uplift and eastward tilting
NEOGENE Pliocene Unconformity
Miocene Basin inversion Alpine Orogeny
PALAEOGENE Oligocene Regional uplift
Palaeocene Intrusion of Cleveland Dyke
CRETACEOUS Upper Regional shelf subsidence
JURASSIC Upper Corallian Group Episodes of regional crustal extension
Middle Ravenscar Group
Lower Lias Group
TRIASSIC Upper Penarth Group Dominantly extensional faulting in west
Middle Mercia Mudstone Group
Lower Sherwood Sandstone Group
Upper Upper Zechstein Group Dominantly extensional faulting in east
Lower Unconformity
Stephanian Basin inversion, regional uplift and erosion Variscan Orogeny
Westphalian Pennine Coal Measures Group Regional subsidence with minor extensional faulting
Namurian Millstone Grit Group
Visean Craven Group Major periods of extensional faulting and basin formation