The catskill delta

312 Chapter 8 gives an updated evaluation of the importance of crystal field theory in the thermochemistry of transition element bearing minerals. Chapter 9 is a short dissertation on the interpretation of crystal structures and mineral properties based on polyhedra (e.g., the SiO4 tetrahedron) as the basic units that constitute structures. The relationships of polyhedra to compressibility, thermal expansion, and compositional changes are discussed. Chapter 10 reviews the models for interpreting the cohesive energy in terms of classic ionic theory and the repulsive energy based on Born and other models. The chapter expands on the various methods for calculating the crystal energy, particularly with the computer program WMIN, and crystal structures with the distanceleast-squares approach. The interpretations of the calculations on several structures and order-disorder problems are given. Chapter 11 looks at phase transitions in terms of relatively simple mathematical relationships between crystal parameters and temperature, pressure and entropy. The chapter also looks at the effect of atom packing and coordination changes and provides a good conceptual view of the equation of state. In total the volume covers a lot of ground in an area of developing interest in mineralogy or mineral physics, the new buzz-word term in the field. The audience for the volume may be narrower than that of earlier Reviews in Mineralogy because of the relatively high level of competence required of the reader, due both to the complexity and theoretical approach. Moreover, it is not complete enough to serve as a text and not simple or uniform enough to provide a clear understanding of the subjects. Some of this is due to the multiple authors and lack of critical editing to produce an even style and adequate notation of concepts, equations and figures. A warning to surface dwellers: whereas some attention is given to the problem of thermodynamic properties at relatively low temperature, the definite focus for much of the volume is interpreting conditions at high temperature and pressure, i.e., liquidus conditions and the mineralogy of the mantle and core. This proclivity i,s both topical due to the attentions of many researchers and a constraint that solid-state thermodynamic properties are both difficult to measure and apply at low T and P, where reaction kinetics and fluid chemistry dominate. Microscopic to Macroscopic may be of most value as a supplement to more basic texts and an introduction to the mathematical approach to studying minerals. GEORGE E. HARLOW (New York, N.Y.)

The Catskill Delta. Donald L. Woodrow and William D. Sevon (Editors). Geol. Soc. Am., Spec. Pap. 201, 1985, viii + 246 pp., US $32.00 (Paperback). Seventy years after Joseph Barrell published his classic " T h e Upper Devonian Delta of the Appalachian Geosyncline" the Geological Society of America, Northeastern Section, at its 18th Annual Meeting conducted a symposium on the subject.

313 This volume presents most of the papers of that symposium and some additional papers. To the generations of students brought up on this classic series of rocks, this is an outstanding volume--outstanding because it strongly reflects the changes in geologic thinking brought about by the plate tectonics revolution and advances in sedimentology. It is exciting reading because the individual authors reinterpret the history of these rocks within the context of an alluvial plain dominated by many small streams. The shoreline varied from muddy to tide-dominated and sandy with local actual deltaic sedimentation. This suggests a pattern that has similarities more to the present day Texas gulf coast than any one individual delta. In addition, paleomagnetic data confirm the geologic evidence for deposition of these rocks and the related Old Red deposits in Europe in tropical paleolatitudes, Sediments originated in mountains to the east and southeast produced by the Acadian Orogeny of the Northern Appalachians. The Appalachian basin in which these rocks were deposited was an elongated depositional basin on the western flank of the Appalachian Orogen. Subaqueous sediments extend from east-central New York, westward into Ohio and southward to Tennessee. The subaerial material is restricted to the central part of the Basin, New York through northwestern Virginia. This volume consists of a preface and 18 papers. Eight are devoted to stratigraphy and sedimentation and emphasize the alluvial coast complex. Five discuss both the continental and marine paleobiology. Three place the Catskill Delta complex within its paleocontinental and plate tectonic setting. A final paper on the economic geology discusses the copper-uranium occurrences within the stratigraphic framework. This is an excellent volume, well edited, illustrated and balanced. It is an excellent summary of present thinking and provides questions for future study. The unity of the volume could have been improved with an expanded preface that summarized the ideas of the individual authors. The editors deserve a great deal of credit for organizing a volume that does far more than simply present new ideas on an old subject. The volume is readable in itself and is a must for anyone interested in a modern interpretation of these well-studied rocks and a classic example of the integration of modern tectonic and sedimentological thinking impacting interpretations of a classic and much studied geologic sequence. R.C. MURRAY (Missoula, Mont.)

Rivers: Form and Process in Alluvial Channels. Keith Richards. Methuen, London,

1982, xi + 358 pp., £stg. 16.00 (cloth), £stg. 8.50 (paperback). Rivers is an overview of river form and process as seen through the eyes of a

geomorphologist concerned with the behaviour of rivers, rather than those of a geologist concerned with sequences of alluvial strata. Its strengths are in fluvial hydraulics and the physical mechanisms involved in channel maintenance, adjust-