Sedimentary Geology, 44 (1985) 173-178 173 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

Book Reviews

Tills and Related Deposits. Genesis, Petrology, Application, Stratigraphy. (Proceedings of the INQUA symposia on the genesis and lithology of Quaternary deposits, USA 1981, Argentina 1982.) E.B. Evenson, Ch. Schliachter and J. Rabassa (Editors). Balkema, Rotterdam, 1983, x + 454 pp., Dfl. 120.00/US $45.00/£stg. 27.00.

This volume is a vehicle for the publication of a series of papers, most of which were presented orally at two meetings of the INQUA Commission on the Lithology and Genesis of Quaternary deposits held in the USA in 1981 and in Argentina in 1982. It has the same camera-ready format as Balkema's previous volume for the Commission, Moraines and Varves (Schli~chter, 1979), and this results in some unevenness in presentation quality with several diagrams being virtually illegible and some papers containing many more typographical errors than others.

The 43 papers are arranged into seven sections entitled Till Genesis (12 papers), Till Petrology (3), Applied Glacial Geology (3), Glaciofluvial and Glaciolacustrine Deposits (4), Pre-Pleistocene Glaciations (4), General (12) and Contributions Re- lated to the Field Excursions (held in Wyoming and Idaho and Argentina, respec- tively) (5). Several of the papers are based on material which has already been published elsewhere, and many are of local rather than general interest. None could be said to be fundamental contributions to the field of glacial sedimentology, but several, especially those in the section on till genesis, do contain interesting and useful ideas. It is, however, disturbing to find that in a volume produced by a commission dedicated to providing a better basis for the genetic classification of glacigenic sediments many contributors continue to make rather indiscriminate use of the term 'till', while others persist in the uncritical and unjustified use of 'shear planes' as a means of explaining the elevation of debris from the glacier bed into the ice.

Of the more interesting papers in the volume, that by Ruszczynska-Szenajch discusses the relationships between lodgement and the glacitectonic deformation of subglacial sediments and it shows clearly how far we are from a good understanding of the mechanics of the lodgement process. The two papers by Muller represent some advance in this direction. Whereas lodgement is conventionally regarded as a process of particle-by-particle accretion against a rigid substrate, Muller shows convincingly that many of the important questions to be tackled in the modeling of lodgement till genesis relate to the decoupling of debris from the glacier and the transition from a dilatant debris-water mixture to a consolidated sediment. Shaw's paper on the forms associated with boulders in melt-out till is an excellent example of the sort of detailed sedimentology which will be required if our understanding of the mechanics of depositional processes is to advance significantly.

Eyles, Eyles and Day provide a thought-provoking discussion of the techniques

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which should be used for the interpretation of glacigenic sediments, and advocate the use of careful field description of lithofacies and logging of vertical sequences of deposits in preference to laboratory analysis of such sediment properties as carbonate content, particle-size distribution and mineralogical composition. It should be noted, however, that the 'objective' diamict lithofacies code proposed for this purpose contains at least one subjective element and that some of the criteria claimed to indicate subglacial shearing (e.g. oriented, glacially shaped clasts) do not in fact do so. Nevertheless, the authors use these methods to produce a reinterpretation of the Pleistocene stratigraphy at Scarborough Bluffs, Ontario as a product of sedimenta- tion by 'pelagic rain-out and ice-rafting' in a large lake. Whilst this approach is undoubtedly valuable, it is not made clear why it is necessary to neglect the information provided by laboratory methods when deciding upon a suitable deposi- tional model for this sequence of deposits. Perhaps the two approaches should be regarded as complementary rather than as mutually exclusive.

In addition to these papers, other valuable contributions come from Easterbrook on the remanent magnetism of glacial tills and glaciomarine diamictons, from Cohen on subaquatic mass flows on glaciolacustrine delta fronts, and from Haldorsen on quartz enrichment in tills. Tills and Related Deposits will be a useful addition to any reference collection relating to glacigenic sediments, but it is one which will probably acquire only a few well-thumbed pages.

REFERENCE

Schliichter, Ch., 1979. Moraines and Valves. Balkema, Rotterdam, 455 pp.

MARTIN SHARP (Cambridge)

Tidal Friction and the Earth's Rotation, II. P. Brosche and J. Si~ndermann (Editors). (Proc. of Workshop held at the Centre for Interdisciplinary Research, Univ. of Bielefeld, Sept. 28-Oct. 3, 1981) Springer, Berlin, 1982, x v + 345 pp., DM 68.00/approx. US $27.20 (paperback).

The subject of tidal friction has always attracted the interest of scientists from many disciplines. Hence, the appearance of a review of a book titled Tidal Friction and the Earth's Rotation, H in a journal with the title "Sedimentary Geology" is not

unexpected. Originally thought to be purely a problem of celestial mechanics, an anomalous

acceleration of the Moon's mean motion was eventually attributed to tidal friction, which transfers angular momentum from the Earth's rotation to the Moon's orbit. Conservation of angular momentum and conservation of energy, then imply that energy must be converted to heat at the rate of about 4.5 x 10-19 erg s-1. Where, in