The End of the Dinosaurs

This book encompasses some great detective work and recounts the birth of the cosmic hypothesis that the effects of a giant impact created on the eart's biosphere led to the exticntion of one very successful life forms on earth... dinosauria.

The descriptions of the crater geology is in terms that the layperson can understand and comprehend. This is ment to pique your interest into Earth sciences and there is and index and bibliography for further study if warrented.

What I found to be the greatest asset in reading this book is the detective work involve in finding the impact area on earth that coinsided with the correct time frame to prove that the impact of an extraterresstial source was one of the contributing factors that caused the extinction of the dinosaurs.

There are photos within this book that show impacts throughout the earth, but the only one that can be linked to 65 millions years ago is Chicxulub in the Northern edge of the Yucatan in Mexico. It amazes me how the geologists work and came up with this site. Iridium was only one of the clues that the geologists used to track down the date of tthe impact, but closer to the impact site there were other telltale signs.

Around the Gulf of Mexico, unusual outcrops are found at the K-T boundary. K-T stands for Late Cretaceous-Tertiary begining. In El Penon, Mexico, a thick sandstone unit is interpreted to be a catastrophic tsunami deposit, laid down by the impact. Where it is capped by a fine clay displaying a wavy pattern, thought to mark the oscilation of the current as the tsunami wave sloshed back and forth across the continental platform. When you take a cross-section of the clay you can really see the the ripple marks, making testament to the current switching directions.

From Mexico, to Haiti and around the Gulf of Mexico you see this clay layer and sandstone around the K-T boundary denoting an impact, but what really piqued my interest here was the fine of the ejecta known as spherules and tektites. Tektites are spashes of the impact melt that take on aerodynamic shapes as they spin through the Earth's atmosphere.

On a different note... why are comet more dangerous to Earth than asteroid... because of the sublimation of the ices heated by sunlight. The jets of gas act as reactors and constantly modify the comet's trajectory. Thus, making comets less predictable than asteroids.

This book takes the reader on a journey into Earth Science and shows us what can happen... fascinating what asteroids, meteorites, bolides and comets can do to the rich complexity of the biosphere, not only then, but today as well.

Yes, we get a history of the scientific controversies leading to the widespread acceptance of a meteorite/comet strike as the cause of the extinction of the dinosaurs. But there's more: the book reviews the evidence for associations between bolide strikes and all of the major mass extinctions in earth history. In prose that's clear, but not dry, Frankel reveals what we know -- and don't know -- about these events. Good illustrations and intelligent speculation round out a first-rate and quite up-to-date overview of a rapidly developing field.

One subtext of Frankel's work is how scientist adapt (and in some cases don't adapt) to new evidence. For example, the Siberian Tunguska explosion of 1908 is now widely acknowledged to have been a strike from a comet fragment, but only 20 or so years ago you could read about it primarily in UFO magazines and "mysteries of the unexplained" books. Because science lacked an explanation for it, the explosion was largely ignored.

I second the recommendation of "The Eternal Frontier."

Frankel's presentation of the subject in the form of a simple, chronological progression was the ideal, from an epicurean's perspective. Firstly, as hors d'oeuvres, it lead the reader through the methodical collation of the data that initially identified the crater and, moving swiftly to the fish course, it set out how the various theories were developed particularly concentrating on the massive global consequences of its formation. It was cooked to perfection!

But sadly, there my meal came to an effective but stuttering end. There just wasn't a main course worhty of the name! In fairness that was solely due to my approach - not Frankel's. I wanted far more than he delivered. So, thank goodness for a good bibliography to act as a damn good cheese board. That had me dashing straight off to Amazon again and the Uni. library!

On the positive side - and importantly - Frankel's approach is straightforward, unbiased and as a result is eminently readable (I read it at a single sitting) - even for someone with a reasonable geological understanding and it certainly doesn't insult the intelligence.

Was I informed? Yes
Was I left wanting for more? Yes

I suppose on that basis it must have been a good read.