Geological Time Scale

© Craven & Pendle Geological Society

As of 2006

A Journey Back In Time

The Quaternary / Tertiary  was a time of great ice ages.  Sediments deposited comprised of till (boulder clay), gravel, and sand; all associated with movement of glaciers.  Our local area demonstrates key features of the Ice Age such as the drumlin field in and around Hellifield, north Yorkshire, and a number of meltwater channels from the spectacular sub-glacial channel of Gordale Scar to the many much smaller meltwater channels around Pendle Hill.  When visiting the Lake District in Cumbria, spectacular features related to highland glaciation can be easily observed i.e. arêtes, corries, u-shaped valleys etc.  This part of Earth history also marked the end of the dinosaurs, the formation of North Sea Oil, and the Alps.  Finally, Britain was seen to migrate from 40°N to 54°N.

There was a more or less complete change in animal fossils following the end Permo / Triassic Mass Extinction.  Britain was located nearer the Equator (20° N).  The palaeogeography (following the Variscan folding in the Permian (0° Equator) was characterised by a shift from arid desert landscapes to more tropical climates.  Although much is known about the land-based dinosaurs that have been popularised by the BBC with 'Walking with Dinosaurs' and more recently real life exploits on Dinosaur Island (Isle of Wight), it is the the oceans that were equally thriving with aquatic activity be it the invertebrates such as the ammonites and the belemnites, and of course the spectacular vertebrates such as ichthyosaurs and plesiosaurs. Plants (flora) such as cycads, conifers and ferns became firmly established on land.

Following the Cambrian 'explosion' of life and early mountain building events of the Ordovician, the climate became much more equatorial in Devonian and Carboniferous times.  Although Carboniferous rocks are common to our region, we are fortunate to have on our doorstep so to speak, the Lower Palaeozoic rocks between Settle & Ingleton. These ancient sediments are intriguing and offer a neat window into a timeframe of 400 million years ago and beyond!  Upper Palaeozoic rocks bring us desert breccias and sandstones of the Devonian giving way to warm shallow seas, deltas, and tropical forests of the Carboniferous.  Britain during this time crossed from the Southern Hemisphere into the Northern Hemisphere.