Halka chronic biography of donald

Review

You don't have to be a rock hound to get motivated by the information in these 170 pages. Fossil forests, dinosaur footprints, and ancient dunes bring out the explorer in everyone. (Sweat magazine)

Past users will find an old friend they can appreciate even more...From the beginning of her writing about geology, Chronic has had the knack of making complex things comprehensible...This book has all the necessary paraphanalia...You don't know what cross-bedding is, or the difference between caliche, chert, concretion, and conglomerate? A handy glossary clarifies all such different concepts. Good black-and-white photos illustrate every chapter, and the publisher has added a section of color plates to enhance appreciation of these wonderful places preserved for our outdoor enjoyment.
s (Southwest BookViews)

A wonderful, non-technical introduction to both the geology and history of 24 national parks and monuments. (Tulsa World)

Filled with stunning pictures, this book is a grea

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Uranium Deposits

The Grants Uranium District extends for almost 100 miles in a band 10 - 20 miles wide, paralleling Interstate 40. This concentration in bands is because the deposits are confined to the old streambeds of the Jurassic era (see the chart of geologic times) and that this old streambed was a natural path for the highway.

But why is the uranium confined to the streambed?

The uranium is concentrated by accumulations of organic matter which create a reducing environment within the ground water which carries the uranium salts. This causes the uranium salts to precipitate out. The plant material may be replaced by the uranium bearing minerals or may act as a nucleus to concentrate the ore.

These accumulations of organic material can be found in stream deposits, especially in the cresent shaped deposits formed in the inner curve of a stream, where it is shallow and the stream slows. It is here that the heavier material will settle out into the deposits called "point-

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Canyon de Chelly

Canyon de Chelly is a long trident shaped canyon in the north west slope of the Defiance Uplift, carved by erosion from running streams. The incredible vertical walls of crossbedded de Chelly sandstone make access to the canyon bottom difficult. As such, it proved a protective home for many ancient and modern native American peoples.

The canyon begins near the crest of the uplift with one arm, Canyon del Muerto, beginning near Tsaile, home of Navajo Community College (now Diné College), with Tsaile Lake at the end of the northern branch. Several of the southern branches of the dendritic system converge in the vicinity of Spider Rock where the vertical cliffs reach heights of 800-1000 feet. At this part of the canyon, the Cutler red beds are exposed beneath the de Chelly sandstone layers. The main branches join at Junction Overlook where several small ruins can be seen high in the walls. This overlook is also a spectacular site from which to watch the