CHAPTER 7 - The Final Moulding

Abstract

This chapter discusses the final molding in geological studies. The Cenozoic Era has so far lasted 65 million years. The main sea-floor spreading in the North Atlantic is presently spread to the area between Greenland and Norway, but the spreading movements were probably complex. The second igneous phase took the form of complex igneous intrusive centers. These occur in Skye, Mull, Arran, Ardnamurchan, Rhum, the Mountains of Mourne, Slieve Gullion, and Carlingford. The complexes comprise large numbers of concentric intrusions such as ring dykes and cone sheets. The ring dykes are of plutonic type. The marked Palaeogene crustal and magnetic unrest in Western Britain must be related to North Atlantic sea-floor spreading in areas west of Britain but with the overall accent on net uplift rather than subsidence. In the London Basin, Palaeocene and Eocene beds are preserved (up to the Auversian Stage) but there are no Oligocene remnants. Several cycles can be identified in these Palaeogene sediments of S.E. England, each cycle being marked by a marine advance and a marine retreat.