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Obras por Keith Heyer Meldahl


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For those interested in anything related to the geology of the American West, a helpful guide and explainer.

Whereas John McPhee wrote compellingly and well regarding the geology of America, he generally did so in the framework of stories of individuals, and the story of the geology itself was often challenging to follow.

Meldahl goes over the same territory - quite literally, also using Interstate 80 as his guide - but provides more thoroughgoing explanations and a lot of charts which allows the reader to be able to more easily "see" and understand how the various processes came to be which led to the formation of the West Coast, the stretching out of the Great Basin, and the uncovering of the Rocky Mountains.

A great way to better appreciate all of the processes by which the American West has come to be.
… (mais)
deusvitae | 1 outra crítica | Nov 20, 2023 |
When it comes to books written about geology for a general audience there is only one definitive classic: Annals of the Former World by John McPhee. It's hard to imagine that anything could really improve upon the classic, but I think Rough-Hewn Land has in many ways added to McPhee's geological chronicle across the western portion of I-80 and is a worthy companion piece. For a complete history of the assembling of California to the exhumation of the Rockies you can't go wrong with either of these books, but there are a few key differences:

The first key difference between Rough-Hewn Land and the Annals, is that Rough-Hewn Land has been written by a professional geologist, that is intimate with the geology of the western United States. McPhee uses his unique narrative style to essentially relate a very detailed interview/tour guide of a local expert. Medahl on the other hand is the expert, so his story is more coherent and complete. He also is better at relating how plate tectonics controls the dramatic landscapes of the American west. I was worried that Medahl's prose would be somewhat dry considering that he is a professor after all, but I was pleasantly surprised that his writing is not only very readable but it is also quite enjoyable. There was even a bit of humor in his writing, that is if you find geologist “humor” to be funny (Beer cans are used at one point to illustrate a concept). And if the geology bores the reader Medahl has included some asides into the regional histories like the California gold rush and why the geology of Utah doomed the Donner Party long before they got to the infamous pass named in their honor. However, it does lack the amateur enthusiasm of the McPhee's books. Medahl like most geologist is quite passionate about his subject, but it's not the kind of enthusiasm of a first discovery.

Another major difference between the Annals and Rough-Hewn Land is that Medahl has peppered pictures and block diagrams to help illustrate the more complicated bits. Geology is a very visual sort of science and without a diagram or picture it's hard to visualize what the author is talking about. The Annals completely lacks diagrams of any kind, making it more difficult to truly understand what's going on for the uninitiated. This is a big plus in favor for Rough-Hewn Land. Another huge factor in favor for Rough-Hewn Land is an appendix that list many of the outcrops complete with GPS coordinates that Medahl visited when putting this book together. So it's possible to construct a field trip along I-80 to get a first hand look at the geology.

Plate tectonics also plays a much bigger part in Rough-Hewn Land. This isn't necessarily a fault of the Annals so much as it is a matter of time. Since Annals has been written our understanding of the plate tectonics and the fault systems of the American west has increased exponentially. Medahl using a modern evidence goes so far as to say that the San Andreas may not be the western most edge of the North American Plate. Instead he proposes that the actual edge of the North American Plate is further inland near the Sierra Mountain range and that there is a smaller plate called the Sierran Plate which should be considered a separate plate from the North American Plate. A very intriguing hypothesis to say the least and the evidence for Medahl's argument is compelling. In this respect Rough-Hewn Land is a welcomed update to the Annals.

Lastly another key difference is the direction of the traverse across the western portion of the United States. Rough-Hewn Land starts on the west coast and finishes in the plains where McPhee chooses to go in the opposite direction. From my point of view this is the proper direction to tell a complete history of the west. It makes more sense to go from the younger events and work our ways backwards in time rather than going from the old to the new. This is not an intuitive notion for sure, but it just makes more sense when you are trying to put it altogether.

Rough-Hewn Land is a proper geology book, not just an update to the Annals of the Former World. I'm now adding a book to a very short list of geology books to recommend to a newly minted enthusiast. It's as enjoyable as it is informative, easy to read and understand, full of pictures and diagrams, and GPS points to get out into the field. Brilliant!
… (mais)
2 vote
stretch | 1 outra crítica | Jun 7, 2013 |
In my rating scheme, 5 star books are rare. Where a 3-star book has to deliver strong basic knowledge, a 5-star book has to make me think about a subject or issue much differently. This book is a a 5-star-a paradigm changer for me in the area of Paleo-Geography, or how the North American continent evolved over billions of years. Due to my background in college where I took a lot of elective geology courses, I consider myself to know more than an average layperson on the subject of geology but less than a professional geologist. In addition to the aforementioned college courses, I've read a lot of fairly technical materials on paleogeography events in North America's past such as the different orogenies that helped shape the current North American West. However, what I lacked was an easy way to "see" all of these processes occuring in sequence in a way that had enough detail to retain vitality important information, yet simple enough to be told in an easy to understand narrative that can be remembered as a story. This book accomplished this for me. Although there was little I hadn't read about before, the way it was presented made me "see" the evolution of the North American continent for the first time. The historical information about the immigrants and the trails is interesting as well. Very highly recommended.… (mais)
Polymath35 | 1 outra crítica | Jun 11, 2012 |
This book is a remarkable mixture of geology and US history. The author is to be commended for this unusual and satisfying study of travel along the Gold Rush trail in its geological as well as historical context. He claims he is one of the "rut nuts," people who seek out the wagon ruts of the trail itself , which started on the Missouri River and went through Nebraska, Wyoming, Utah, Nevada, and into the Sacramento gold fields. In about 20 years, between 1849 and 1869, roughly half a million people made the journey.

Each chapter of the book alternates between a description of the travel in covered wagons, with quotes taken from the diaries of the travellers, and a geological explanation of the territory through which they sojourned. This mixture worked well for me, with the one type of material illuminating the other. The maps and diagrams were of great help, and the author's personal comments and sense of humor kept the text from being too dry.

As the author explains, the fuel for the wagon trains was grass, which fed their animals. The migrants had to wait for enough grass to grow along the rivers in the spring before they could start out. This meant that May was the departure month, and that the trail had to follow the rivers. At the other end of the journey, the migrants had to climb over the Sierra Nevada passes before the snowstorms closed them in October. So there was a brief five month period to make the trip, which was just manageable. However, it meant crossing the Nevada desert in August, the most hellish time of the year. The description of this feat is indelible.

The final poignant photograph of the book from 1869 shows the newly constructed intercontinental railway passing one of the last wagon trains.

This is a unique and vivid work which will be appreciated by those who like practical historical background.
… (mais)
Wheatland | 1 outra crítica | Aug 1, 2010 |





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