Quaternary of Northern England
The Quaternary Period is an integral part of the Cainozoic Era. It is a period of earth history dominated by major climatic changes and characterised by the growth large ice caps in temperate mid-latitudes. The Quaternary is divided into two parts, the Pleistocene (from 1.6 MA to 10 000 years ago) and the Holocene (the past 10 000 years). Although the Quaternary Period is commonly thought of in terms of 'Ice Ages' bear in mind that 'Ice Ages' have occurred throughout geological time.
The Base of the Quaternary Period
There are a number of contentious views concerning the base of the Quaternary period - the usual date being about 1.64 million years ago (MA). The International Union of Geological Sciences suggest 1.905 MA (Shackleton et al 1990). In the Netherlands the preference is for 2.45 MA and to cap it all (pardon the pun) NW Europe has a major faunal change at c.2.5 MA. It is no surprise then to know that the 'Stratigraphic Commission of the International Union for Quaternary Research' (INQUA) is currently searching for a suitably defined boundary stratotype. Note the similarity with what happened with the Mid-Carboniferous Boundary!
Divisions of the Quaternary Period
The traditional view of the Quaternary is a series of alternating periods of cold and temperate time frames. There was an initial pre-glacial phase, followed by one when glacial and periglacial environments alternated with temperate ones. Interglacials are temperate, climatic intervals between cold stages. Moreover the precise number of cold and warm phases is questionable. For many years there was thought to have been 7 cold stages together with 8 temperate ones had been recognised in the British Pleistocene. As a result of analysis of the sediments from deep sea cores, and the introduction of oxygen isotope stratigraphy, the following climato-stratigraphical stages have been proposed for Britain (after Mitchell et al 1973). These are presented in the diagram above.