Book review:

This book aims to help the reader analyze deposition of stratigraphic sequences accurately and objectively. A complete understanding is probably not possible, because many of the controlling depositional factors, such as details of climate, oceanic conditions, regional settings and morphology, are not now recoverable. Visher's next-best approach provides access to a large data bank of sedimentary attributes of multiple stratigraphic examples beyond the reach of most practicing workers, and a computer-driven multivariant comparison (DE-XPERT system on accompanying CD-ROM). This broad-based approach should minimize the bias of limited personal experience and geologic lore, and maximize a more objective approach.

According to Visher, Holocene examples are best for comparison because they include more complete climatic, regional environmental, and geomorphic data. Thoroughly studied ancient examples are also included in the data bank. The DE-XPERT system is supposed to determine relative probabilities of possible origins for a given stratigraphic interval.

Most of the book is a valuable summary and organization of ancient and Holocene examples into depositional systems and settings. Tectonic controls and basin settings of stratigraphic sequences are discussed. Depositional systems are then organized into fifteen siliciclastic and six bioclastic and evaporitic systems, ranging through nonmarine, fluvial, deltaic, coastal, shelf, and deepwater systems. Each of these systems is thoroughly discussed and many examples are summarized, with lists of attributes for each depositional system to help with comparisons.

A section on how to reconstruct depositional history is very helpful. A discussion of information systems summarizes major methods for determining stratigraphic attributes. These methods include seismic sequence and facies analysis, biostratigraphy and graphic correlation, textural attributes and sedimentary structures, petrophysical attributes, and various types of facies mapping. Historic resumes of how stratigraphic concepts and approaches were developed place these techniques into perspective.

Other sections in the book include discussion of the DE-XPERT program and the author's philosophy of stratigraphic analysis. Visher stresses the need for models and stratigraphic themes. He also emphasizes that only time-stratigraphic units deposited within a given time-frame should be analyzed. An extensive bibliography is included.

As a textbook, this book is strictly for the graduate level, or for workers in the field, because it presupposes a rather complete background of tectonic and stratigraphic concepts and terminology. It is very valuable as a reference and historic resume for a wide variety of tectonic and basinal settings, depositional systems, and stratigraphic examples. Abundant illustrations are mostly taken directly from references, with very succinct summary discussions in the text. Most of the examples are from studies published in the 1960's, '70's and '80's, when many of the depositional systems were being described in the literature. The book suffers from inclusion of only a bare minimum of papers from the early 1990's, and practically none from the later '90's. Especially missing are seismic and well-log examples of deepwater depositional systems such as those in the Gulf of Mexico, offshore Brazil, South African outcrops and offshore examples, or the Delaware Basin outcrops. Three-D displays of seismic attributes such as amplitude, frequency, and continuity can be helpful in analyzing sedimentary attributes. These deepwater systems are the bread and butter of the oil industry today.

The book contains numerous annoying typographic errors, grammatical mistakes, and mislabeled figures. Many of the figures are reprinted at such small scales that texts and legends are practically illegible. Examples of redundancy occur in the text. In the introduction to the book, at the beginning of major sections, and in the summary sections on depositional themes, the author repeats elaborate discussions on his philosophy of stratigraphic analysis, and the need for the multivariate approach. I personally was convinced the first time he stated them. A more careful writing and objective editing would have improved and shortened the text.

In spite of the above, this book contains much valuable stratigraphic information and provides a good reference for examples. I thoroughly enjoyed being reminded of a wide range of long-forgotten stratigraphic sequences. I did not open the CD-ROM because of my lack of equipment, and did not get to put my favorite stratigraphic puzzles into the DE-XPERT system.

This book gives a new dimension to the science of stratigraphic analysis. I hope the system it advocates can be used to spark new enthusiasm where it is much needed.

Mitchum is a consulting geologist in Houston.

For a beginning mineral collector the most daunting question is, “Where do I go to collect?” Typical mineral and gem guides consist of a map at a scale of 1:1,000,000 (or greater) with an “X marks the spot” designation that is often the size of a small city. Directions often read something like: “Drive about four miles out of town until you see a big cottonwood tree and turn left at the next opportunity. Continue for a while until the second cattle gate. Park about a mile further down the road and walk up the gentle hill on the left. At the top look for a group of three hills and search near the base of the one in the middle. You’ll find crystals everywhere. You can’t miss ’em.” Six hours later you’ve driven down every dirt road within 10 miles and seen 15 different groups of three hills and haven’t found a single crystal. That kind of experience can put the damper on any budding rockhound.

Precise directions and some idea of what to expect at the collecting area are absolutely essential pieces of information to the beginner. In the wide-open spaces of Arizona, even the experienced mineral collector trying a new area needs to know where and what to look for.

Adding to the beginner’s problem is the fact that mineral collecting spots are often closely held secrets. There are, of course, the well-known (i.e., completely picked over) spots where it is easy to spend a day of backbreaking work for a few mediocre specimens that you might be able to make presentable with a few more hours of cleaning. The best spots are mostly passed on by word-of-mouth. There are a few journals published for the mineral collecting community that describe mineral locales, but it is not likely that a beginning or even intermediate mineral collector would have access to a complete set of The Mineralogical Record. Many would-be mineral enthusiasts call our office seeking information on how and where to get started. Until recently, there had not been a single volume that I felt comfortable recommending. What a pleasure to finally be able to recommend a single reasonably priced volume that dispenses enough up-to-date lucid information to satisfy any mineral enthusiast.

Minerals of Arizona: A Field Guide for Collectors by Neil R. Bearce is one of the best mineral collecting guides I have seen. He describes 57 areas in Arizona for collecting materials, including lapidary rough and fossils; but concentrates on mineral specimens. Every description is accompanied by a reproduction of the portion of the 7.5-minute U.S. Geological Survey topographic map (at a slightly reduced scale) for the general area with annotations showing the best routes and small circles marking the actual collecting sites. The first paragraph of each area description is a precise set of directions listing exact mileages with highway designations and road names wherever available. This is first-hand information. In the months before publication Bearce personally visited and collected at every site listed. Each area is also rated for difficulty of access, difficulty of getting around the actual site, and difficulty of extracting the material. Even the best seasons for collecting are listed for each area, an important consideration in a state like Arizona where the climate is varied and extreme.

The guide begins with a concise introduction followed by a short section on rockhound etiquette. Following are longer sections on mineralogy (introductory level) and a listing of the scientific properties of the minerals discussed in the main section. Many of the 57 collecting areas host multiple collecting sites. Each site description contains a description of how the minerals occur and how the minerals appear in situ. Each area description includes at least one black-and-white photo, usually of a key landmark along the route or of the actual sites. The book also features a 16-page section of full-color photographs of representative minerals from many of the areas.

Besides well-known sites, some previously known sites are described whose locations were not widely known or disseminated. Some within the Arizona mineral-collecting community have suggested that Bearce should not have published some of this information because the areas are too good and should have been kept “secret.” The book also lists some new sites that, to my knowledge, had not been described in print. I’ve checked some of his new sites and found the directions to be accurate and the collecting to be decent.

The only shortcoming of this guide is a lack of consistent emphasis on land status of the described areas. The introduction includes a caveat urging the user to get permission from private property owners, but overall the book offers little information about the land status and ownership of individual areas. As a matter of fact, the publisher has begun hand stamping a warning on the first page of one of the area descriptions because the owner of that particular area has made it clear that the land is private and trespassing is not permitted.

Anyone traveling to Arizona to collect minerals would be well advised to purchase this volume. A potential visitor could easily select enough areas to fill their time in the state and get a good idea of the collecting conditions and type of vehicle and equipment necessary. Mineral collectors who live in or near Arizona could also make excellent use of this volume. I’ve noted several areas that were on my “got to check that out” list. With the aid of Minerals of Arizona I know I won’t have to waste time searching for the exact locations.

Trapp is a geologist with the Arizona Geological Survey. E-mail: Trapp_Richard@pop.state.az.us

On the shelf

Earth Sciences and Archaeology, edited by Paul Goldberg, Vance T. Holliday, and C. Reid Ferring. Kluwer Academic/Plenum Publishers (2001). 513 p. ISBN 0-306-46279-6. Illus. Hardcover, $120.

Energy and Environment: Technological Challenges for the Future, edited by Y.H. Mori and K. Ohnishi. Springer (2001). 320 p. ISBN 4-431-70293-8. Illus. Hardcover, $144.

Geology: A Self-Teaching Guide by Barbara Murck. John Wiley & Sons, Inc.(2001). 328 p. ISBN 0-471-38590-5. Illus. Paperback, $19.95.

Geology of New York: A Simplified Account, edited by Y.W. Isachsen, E. Landing, J.M. Lauber, L.V. Rickard and W.B. Rogers. New York State Museum and New York State Geological Survey (2000). 294 p. ISBN 1-55557-162-X. $21.95.

Inside the Hurricane: Face to Face with Nature's Deadliest Storms by Pete Davies. Henry Holt and Company (2001). 272 p. ISBN 0-8050-6611-X. Paperback, $14.

International Relocation: A Practical Guide to Living & Working Overseas by Marc Bond with Rita Bond. The American Association of Petroleum Geologists (2000). 457 p. ISBN 0-89181-821-9. Paperback, $29.

Interpreting Remote Sensing Imagery: Human Factors, edited by Robert R. Hoffman and Arthur B. Markman. CRC Press (2001). 289 p. ISBN 1-56670-413-8. Illus. Hardcover, $89.95.

Mammoth: The Resurrection of an Ice Age Giant by Richard Stone. Perseus Publishing (October 2001). ISBN 0-7382-0281-9. $26.

U.S. Geological Survey

I-2636. VERMONT. Bedrock geologic map of the Saxtons River 7.5’ x 15’ quadrangle, Windham and Windsor Counties, Vermont by N.M. Ratcliffe and T.R. Armstrong. Prepared in cooperation with the Vermont Geological Survey. 2001. Scale 1:24,000. Two color sheets accompanied by 21 pages of text. $14.

The Saxtons River quadrangle provides a wonderful example in western New England of how multiple orogenic events can be delineated when structural and isotopic analysis is integrated with detailed geologic mapping. An Ordovician arc terrane is found on both sides of billion-year-old North American crust, placed there along a fault zone that marks the terrane boundary. North American crustal rocks and overlying Late Proterozoic rift clastics (now a high-grade metamorphic terrane) occur within the core of a large dome structure that separates the cover rocks into a western sequence, characterized by intense Middle Ordovician deformation (the Taconic Orogeny); and an eastern sequence, comprising rocks that have a strong Devonian metamorphic and deformational overprint related to the Acadian Orogeny. This work was conducted as part of a multi-year, cooperative agreement between the U.S. Geological Survey and Vermont to produce a new state geologic map at the scale of 1:100,000.

I-2673. ALASKA. Geologic map of the Arctic quadrangle, Alaska by W.P. Brosgé, H.N. Reiser, J.T. Dutro Jr., R.L. Detterman and I.L. Tailleur. 2001. Sheet 1 map scales are both 1:200,000 and 1:750,000, and Sheet 2 scale is 1:200,000. Sheet 1 is in color and Sheet 2 is in black and white. Accompanied by 38 pages of text. Available free at: geopubs.wr.usgs.gov/i-map/i2673/

I-2682. VERMONT. Map showing slope failures and slope-movement-prone areas in Vermont by C.A. Baskerville and G.C. Ohlmacher. Prepared in cooperation with the Vermont Geological Survey. 2001. Scale 1:250,000. One color sheet. $7.

I-2696. MICHIGAN. Geologic map of the Keweenaw Peninsula and adjacent area, Michigan by W.F. Cannon and S.W. Nicholson. 2001. Scale 1:100,000. One color sheet. $7.

MF-2368. ARIZONA. Geologic map of part of the Uinkaret volcanic field, Mohave County, northwestern Arizona by G.H. Billingsley, W.K. Hampton, J.L. Wellmeyer and S.L. Dudash. Prepared in cooperation with the National Park Service and Bureau of Land Management. 2001. Scale 1:31,680. One color sheet. Available free at: geopubs.wr.usgs.gov/map-mf/mf2368/

To order USGS maps: Contact USGS Information Services, P.O. Box 25286, Denver, CO 80225. Phone: 1-888-ASK-USGS (1-888-275-8747).

Peter Lyttle compiles the Maps section and is acting coordinator for the USGS National Cooperative Geologic Mapping Program. E-mail: plyttle@usgs.gov

www.oregongeology.com
Whether or not you’re an Oregonian, you’ll appreciate this Web site hosted by the Oregon Department of Geology and Mineral Industries. Its home page boasts, “Oregon’s spectacular scenery is a direct result of awesome geologic forces acting on the land for millions of years.” In this same vein, the site highlights the state’s geological assets and how to find them. Points of interest include the John Day Fossil Beds National Monument, how and where to pan for gold, and how to recognize a Thunderegg, Oregon’s official state rock.

www.goodearthgraphics.com/virtcave
The Virtual Cave site lets you explore four different types of caves. Detailed text and photos explain sea caves and erosional caves. Solution caves and lava tube caves have clickable image maps linking to more info on soda straw stalactites, Baldacchino canopies, cauliflower Aa lava and tubular lava helictites. A fast Internet connection is a plus — these photos may take a while to download.

www.athro.com/geo/hgframe.html
Unless you carry a geological time scale in your wallet (the trademark of my university’s paleontology students), you’ll have to rely on memory to pass this site’s Geological Time Line Quiz. Fill in the eons, eras and periods that span Earth’s history, hit Submit and prepare for responses like, “The Neogene was not found.” After this humbling experience check out the site’s Metaphors for Geologic Time to fill in your Earth history knowledge gaps.

On the Web this month was compiled by Jann Vendetti
 

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