Looking at the other reviews I was prompted to write this one in an effort to redress the objectionable references to pseudo-science. Derek Allan spent a lifetime in teaching and in his spare time spent over 40 years collecting and cataloguing geological information and this book is the culmination of all that research. It was published in the latter years of his life which is why some of his sources appear outdated. However, unlike other authors on the end of the Pleistocene the authors of this book include a vast amount of material from Russian field research published in obscure and difficult to get hold of journals and as such this work has a novel twist that other western geological authors do not possess. There are some surprising similarities between this model and the more recent Firestone and West et al theory of a cometary airburst at the beginning of the Younger Dryas (the end of the Pleistocene). The actual chronology is different, with the Pliocene overlapping with the Pleistocene in the Allan and Delair model, an idea that has been overtaken by the sheer weight of modern research, and in particular ice cores, ocean sediment cores, and various dating methodologies. In that respect this book is in many ways out of date - but the research spans a very long period of time, research that is often ignored by modern geologists and commenters. As such, some factors in this book can be taken with an upraised eye, but generally they are pointing a finger at a real anomaly, something dramatic happened at the end of the Ice Ages. Earlier ice ages did not result in the extinction of large numbers of species, far from it as they appear to have thrived not only during the cold episodes but through the various warm interglacials, some of which were warmer than average temperatures nowadays. Then we have those huge depressions in the crust that are in places up to four thousand feet deep and filled with the mixed remains of animals, plants, trees, rocks and gravels etc They are evidence I would have thought but evidence that is generally passed over by scientists simply because they do not fit the pattern of the uniformitarian model. The same with all those Pleistocene bones, jumbled and mixed, regularly found by potholers in the 20th century, when most of Britain's cave systems were explored. The tar pits in California are another huge hotchpotch of mangled bones of extinct and surviving species that are not adequately explained. Comments in textbooks tend to concentrate on individual specimens and rarely describe or mention the sheer multitude of remains - you have to read books like this to find out about this factor. That is strange science in a way - ignore what does not fit the consensus. Not really very objective - and that goes for those reviews that describe this book as pseudo-science. Mainstream science is just as prejudiced - possibly more so. It has a series of consensus views and evidence is manipulated into that model. If the evidence does not fit it is ignored - and I've just illustrated how the extinctions at the Pleistocene are ignored because they raise embarrassing questions. Books like this raise embarrassing questions too - that is why they are dismissed as pseudo-science. Clear case of poppycock.