دانشجويان و دانش‌آموختگان زمين‌شناسي

دانلود کتاب حوادث بزرگ و کوچک: دلایل انقراض عظیم

Catastrophes and Lesser Calamities

The Causes of Mass Extinctions

By

• Publisher:   Oxford University Press, USA
• Number Of Pages:   240
• Publication Date:   2005-08-06
• Sales Rank:   217187
• ISBN / ASIN:   0192806688
• EAN:   9780192806680
• Binding:   Paperback
• Manufacturer:   Oxford University Press, USA
• Studio:   Oxford University Press, USA
• Average Rating:   4
• Total Reviews:   6

Book Description:

This is a book about the dramatic periods in the Earth's history called mass extinctions - short periods (by geological standards) when life nearly died out on Earth. The most famous is the mass extinction that happened about 65 million years ago, and that caused the death of the dinosaurs. But that was not the worst mass extinction: that honour goes to the extinction at the end of the Permian Period, about 250 million years ago, when over 90% of life is thought to have become extinct. What caused these catastrophes? Was it the effects of a massive meteorite impact? There is evidence for such an impact about 65 million years ago. Or was it a period of massive volcanic activity? There is evidence in the rocks of huge lava flows at periods that match several of the mass extinctions. Was it something to do with climate change and sea level? Or was it a combination of some or all of these? The question has been haunting geologists for a number of years, and it forms one of the most exciting areas of research in geology today. In this book, Tony Hallam, a distinguished geologist and writer, looks at all the different theories and also what the study of mass extinctions might tell us about the future. If climate change is a key factor, we may well, as some scientists have suggested, be in a period of mass extinction of our own making.

Date: 2007-01-10   Rating: 4
Review:

Tough read but worth it

This compact little book has more information about so-called mass extinctions than you may want to know. It's a tough read for the non-geologist/scientist and I found I had to take it in small bites. BUT, it is worth the effort. His analysis of causes, his conclusions and his final overview of current global warming are excellent. He certainly puts the end to ideas of extinctions which happened overnight and shows how a combination of factors may have been necessary to achieve the death toll of most living things.

Date: 2006-10-11   Rating: 4
Review:

The author should stick to science

This book presents a great deal of information on mass extinctions, and it provides an excellent overview of how geologists and paleontologists gather evidence of the causes of mass extinctions. What they can garner from the geologic record is amazing. He also discusses the theories of other geologists in a very respectful manner. Dr. Hallam pokes holes in the asteroid theory for the mass extinction 65 million years ago--wiping out the dinosaurs--although he says that the asteroid may have delivered the final blow to the already dwindling species of dinosaurs.

My only quibble is that the author includes some little anecdotes about his research trips and the local people who helped him. He notes that he doesn't want to sound patronizing, but he does--VERY patronizing to the point of being offensive.

However, this book does an excellent job of explaining what we can learn--and what has been learned--from the geologic record.

Date: 2006-09-21   Rating: 3
Review:

Requires patience and some prior knowledge

Hallam impresses me as a careful scientist who has assimilated an immense amount of material. I enjoyed this book, even when the detail and vocabulary were daunting. However, I don't think it was particularly well written, and if you don't already have some background in earth history, do not even think of starting with this book. The book is written in kind of a monotone, without enough focus on the key ideas, and without enough summary material (despite a previous reviewer, most chapters don't end with any summary). Figure 9.1, extinction name vs contributing causes, does provide a nice overall summary, in fact all the figures are very helpful. The subject is inherently confusing because there are relatively few conclusions on which there is consensus.

It is probable that only the extinction involving the dinosaurs, at the end of the cretaceous, was caused by extraterrestrial impact; it is "volcanism" which is actually associated with many extinction's. Think not of a terrestrial volcano blowing its top, but sustained undersea activity which raises the seabed enough to cause worldwide inundation, and the release of sufficiently large quantities of dissolved methane to cause a greenhouse effect. Associated with volcanism is the impact of tectonic movement, with its consequences for global climate and ocean currents. Remember that for older extinction's, the benthos (organisms living on or in the sea bed, most importantly on continental shelves) was particularly important, and warming waters, as well as deeper waters, could cause a lack of dissolved oxygen. Warm water holds less oxygen, and this is aggravated by a lack of strong ocean currents which are normally driven by large temperature gradients between polar and tropic waters.

The last chapter on extinction's caused by humans is very readable and can be read by itself. For readers interested in earth history, I recommend Nick Lane's book, "Oxygen", part I. Even though it focuses on atmospheric oxygen levels, many important concepts are explained.

Date: 2006-08-10   Rating: 5
Review:

Theory of Mass Extinctions for the Serious Beginner

Other reviews on this page give a fair idea of the contents of this book and so, as with most of my science reviews, my main goal here is to describe the technical level so that potential readers can decide if this book is for them. (If you're interested, you can click above on "See all my reviews" for more. There are at least two pages.) This is especially urgent since one of the previous reviews (of the paperback edition) says that Hallam "keeps his use of professional terms within the reach of the basic reader..." while another reviewer (of the hard cover) says the book is more appropriate for specialists than for general readers. I have seen only the paperback and it has a LOT of jargon, words such as "Frasnian", "tectonoeustatic", "chronostratigraphy", "brachiopod", and "paraphyletic". I still say this is a book for beginners because it doesn't require much prior knowledge. All of the terms the reader will need to know are defined in the book; many are defined more than once, in case the reader has forgotten in the meantime. (That will often be the case.) One doesn't need to know mathematics, geology, chemistry, or the history of life.

There are also a great many undefined terms but, in general, there is no need to know the definitions. They are mainly names of kinds of organisms and the point Hallam is making is that a lot of kinds of organisms went extinct at the same time. For example, it doesn't matter if you don't know how rugose corals differ from other corals; the point is that the kinds of animals that built reefs before the Permian extinction disappeared in that extinction. Some readers will be uncomfortable at first with getting the gist of an argument without understanding all the words, but I think most will get used to it.

Hallam also has a very good chapter on the effect of mass extinctions on evolution. In particular, a pair of graphs shows a remarkable change in diversification of marine life about the time of the Permian extinction and another in land life at the time of the K-T extinction. I have always been interested in evolution, so this is the most interesting thing about mass extinctions for me. And there is a final chapter on the Holocene mass extinction, which is currently being carried out by humans.

There are two other books on mass extinctions which I have read and reviewed and which may be of interest. One is by Hallam and his colleague Paul Wignall. It covers essentially the same ground as the current book, but it is at a more technical level and it assumes the reader knows many of the terms that are used in the current book. The specialists that another reviewer mentioned would be much better off going directly to Hallam and Wignall, as would anyone who I familiar with the 5 words I cited above. Readers who absorb much of the vocabulary in Hallam might well like to go on to Hallam and Wignall.

The other book is by Douglas Erwin. This is more technical than Hallam but less technical than Hallam and Wignall. It also covers only one mass extinction, that of the end-Permian, and so there is less vocabulary to keep track of. The end-Permian is the most exciting for me, not only because it was more massive than the others, but even more so because one of the groups that was nearly wiped out was the the synapsids, the ancestors of mammals. One more extinction in that group and we might not be here. Erwin also has an excellent discussion of the significance of carbon isotope ratios.

In sum, if you want to learn the science of mass extinctions and not just descriptions, if you know only a little about palaeogeology and marine palaeobiology, if you like to work at learning, and if you're not intimidated by a lot of new words, This book is an excellent place to start. Some readers will find it so complete that they won't need more.

Date: 2006-06-17   Rating: 5
Review:

Supurb overview on the topic of extinction

Catastrophes and Lesser Calamities by Tony Hallam is a well written book on the topic of biological extinction through time . The volume is essentially a rewrite of the book he and Dr. Wignall wrote together in 1997 (Mass Extinctions and their Aftermath). While the latter is far more technical and probably more than the average person with an interest in paleontology and extinction events is willing to undertake, the present volume is written very much with the a vocational reader in mind.

The book has a very readable style, revealing the author's erudition in its sentence style, vocabulary choices (my favorite is "depauperate" with respect to a description of the diversity of a particular fauna), and thorough knowledge of the recent pertinent literature. He keeps his use of professional terms within reach of the basic reader and provides a glossary of terms at the end of the book. While he has some "attitude" with respect to certain issues, he addresses everything in a thoroughly gentlemanly manner, giving credit to the work of others, and when he disagrees with findings makes his point graciously and with evidential support. Students writing papers would do well to study his style and approach to argument.

The earlier book with Wignall addressed extinction as a series of specific events. It looks at each event, discussing the date, type specimens, and facies locales throughout the world that support the likely diagnosis of mass extinction and reviews the scientific data that suggests how they might have come about. The present book looks at extinction as a process that effects life and evolution through time. While specific events are discussed in an organized way, the author focuses more on the nature of proposed extinction processes. The most commonly and widely known of these causes are the bolide impact, anoxic aquatic or atmospheric conditions, volcanism, and climate change, each of which is examined in depth using specific extinction events to discuss the data.

The section I found most interesting was "Pulling the Strands Together." This was because it reminded me of other authors I've read on other subjects, the topics of which seem to have implications for extinction as a process.

One is Stuart Kaufmann's work on self organized criticality which discussed, among other things, a topography of fitness within a set of parameters. He introduced a diagram illustrating, through the rise of peaks from a baseline terrain, that life tends to organize itself in such a way as to make optimal use of the fitness terrain. He notes that, when conditions are altered especially when rapid, those at the peak are not able to hop from one peak to a better one. Their failure to adapt brings about extinction, and others along the lower slopes make a transition to a new peak fitness profile. As Hallam notes, catastrophes may occur too quickly for many taxa to adapt in a Darwinian manner, which leads to disappearance. However, where change is slow enough some taxa that seem to have disappeared may in fact simply have evolved into a descendant species. They sort of back down the old fitness slope and head off in a new direction.

Another author that is brought to mind is the theorist Per Bak, who studies self organized criticality and event probability. The discussion of periodicity/episodicity of extinction in Dr. Hallam's work reminded me of Dr. Bak's discussion of earthquakes, landslides, and similar events. In this case, the author notes that the frequency of occurrence of any possible event will lie along a curve that measures the probability of a given magnitude. In this instance, extinction might be seen as ranging from extinction of a single of species to the end of all life on earth. In short, Bak believes that all events that can occur will do so, but that they have a different probability of doing so. As with the disaster in New Orleans during Hurricane Katrina, it isn't a matter of "if" but of "when" the event will occur. The events as they occur through time, however, form an irregular curve with many small peaks punctuated with the random introduction of a few very big ones. The issue for disaster planners and others is that of prediction and preparation, so an effort is made to find a "periodicity" in the data that isn't necessarily there to find. This sounds very much like Dr. Hallam's discussion of the attempts to pin down a periodicity in the data of extinction events. Humans are very good at seeing patterns in random data, but ultimately all that can be said is that "if it has happened, it can happen."

I'd recommend the book to anyone with an interest in paleontology, paleoecology, and extinction events. It would make a lovely book for an introductory course on earth history, or in paleontology, and an excellent syllabus entry for a course in earth science for teachers.

A wonderful book, full of information, and well written.

دانلود