Glossary of geological terms
glaciofluvial deposits / gwaddodion ffrwdrewlifol
Sands and gravels laid down by water originating from glaciers and ice-sheets during the ice ages.
Gondwana(land) / (Tir) Gondwana
Former super-continent which came into being towards the end of the Precambrian era. It comprised modern-day Africa, South America, Australia, Antarctica and India. Its collision during the Carboniferous period with the former continent of Laurasia resulted in the formation of the super-continent of Pangaea.
Goniatites / Goniatites
Fossil shells of an extinct group of molluscs resembling ammonites. They can be found within ‘marine bands’ within the Carboniferous age rocks of the area where they are useful as marker horizons.
Grammysia Beds / Gwelyau Grammysia
A succession of fossil-bearing mudstones laid down during the Ludlow Epoch of the Silurian Period.
Grey Grits / Grutiau Llwyd
Coarse sandstones which in some places overlie the Plateau Beds and were laid down during the late Devonian Period.
grike / graic
See Limestone pavement.