Mary Hill (2)

This was a surprise five star read for me. A perfect story of the Sierra Nevada formation in California for a person who is interested in the things they see around them, but doesn't want to go to college classes to understand them. Mary Hill not only makes the geology understandable for non-geologists, she makes it rather exciting!

This book gives an overall understanding of the forces which combined to form the Sierra Nevada mountain and valley region of California. It also has many maps and charts which show where one may go to observe the effects of those forces. My husband and I are looking forward to a time when the forests are not burning down so that we can make road trips and find the places described in the book.

She describes the types of rocks to be found, the forces which made them, and includes charts and maps to find those as well, including the names of various buildings in the little towns which were built out of some of those types of rocks. Delightful field trips in our future!… (mais)

A very interesting, well-written discussion of the geology of the Sierra Nevada mountain range and the area around it that it's affected, covering both the structure of the rocks (as currently understood) and the human-scale history of the people studying it, from geologist to gold-miners. This is a second edition of the book, with (we are told in the introduction) a greatly expanded discussion of plate tectonics and their effects in the region. The first edition was written when the idea of plate tectonics was new, and contained a bare mention of the theory and its possible relation to the structure of the mountains. The first chapter or two is pretty strict geology, with discussions, figures, tables, and glossaries of the different kinds of rocks (by chemical or physical structure) that can be found in the Sierra Nevada mountains. Theoretically interesting, but rather dry - I slogged through that part, even though I'm an interested amateur. However, it did help give me the vocabulary I needed later on. Most of the rest of the book thoroughly intertwined discussion of the rocks and structures of the mountains, and the people who discovered, used, or suffered from the effects of these structures; there was just enough human interest to liven up the geology, and plenty of solid geology to explain the human actions. From the first scientific expeditions into the mountains, to the practical knowledge (and the theory underlying it) of the gold-miners trying to determine where to dig next, to the frequent earthquakes and past (and possibly future) volcanic eruptions in the mountains, it was a fascinating explanation of what we see now and how it got that way. The several chapters covering glaciation taught me the reasons for a lot of things I've seen many times and never knew the reasons for, like the hanging waterfalls of Yosemite Valley - tributary glaciers or streams flowed into the great glacier that filled the valley, and because their water or ice only flowed onto the surface of the glacier the channels they carved didn't erode down the new cliffs the glacier made. When the glaciers melted, what was left was water channels high up at the top of a vertical cliff, leading to the beautiful leap of water in the hanging waterfalls. It makes perfect sense, but I'd never thought of it. I learned a lot, I enjoyed the book, and I'm very pleased I read it. I may well read it again, in a few years.… (mais)