During the Pleistocene, the modern continents were essentially at their present positions; the tectonic plates on which they sit have probably moved at most 100 km (62 mi) from each other since the beginning of the period.
Climates during the Pliocene became cooler and drier, and seasonal, similar to modern climates. The formation of an Arctic ice cap around 3 million years ago is signaled by an abrupt shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic and North Pacific Ocean beds.
We examine the relative successes and weaknesses of this cutting edge science.South America became linked to North America through the Isthmus of Panama, bringing a nearly complete end to South America's distinctive marsupial fauna.The formation of the isthmus had major consequences on global temperatures, because warm equatorial ocean currents were cut off, and the cold Arctic and Antarctic waters lowered temperatures in the now-isolated Atlantic Ocean.A major event is a general glacial excursion, termed a "glacial". During a glacial, the glacier experiences minor advances and retreats.The minor excursion is a "stadial"; times between stadials are "interstadials".Each glacial advance tied up huge volumes of water in continental ice sheets 1,500–3,000 m (4,900–9,800 ft) deep, resulting in temporary sea level drops of 100 m (330 ft) or more over the entire surface of the Earth.During interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. Antarctica was ice-bound throughout the Pleistocene and the preceding Pliocene.C, TL and U–Th, and in recent years the efficacy of each has been the subject of considerable debate.We review here the use of the U–Th technique to date the formation of calcites that can be shown to have stratigraphic relationships to cave art.We focus particularly on two recent critiques of the method.By using specific examples from our own work using this method in Spain, we demonstrate how these critiques are highly flawed and hence misleading, and we argue that the U–Th dating of calcites is currently the most reliable of available chronometric techniques for dating cave art.