This is an attractive well-illustrated book and there is much that the amateur and student readerships targeted will find interesting and useful. The colour pictures of rocks are excellent, although some of the line drawings could be improved. Six areas of sedimentary study are introduced in successive chapters with a useful glossary at the end.
Chapter 1 introduces the basic scientific tenets of sedimentology. However, the speed at which these are presented may make them a challenge for readers unfamiliar with the material. It is good to see the origins of the principles underpinning the science described, but the order in which they appear seems odd. The key figures were Nicholas Steno (1638–86), who first demonstrated the principle of superposition, and William Smith who, using this principle, made the first strata-based geological maps in the 1790s. However, the author has chosen to discuss the concept of facies, introduced by Amanz Gressly (1841–65), before either of these. It is admirable that this term is properly defined, when it is so often misapplied, but surely the chronology is important because Gressly would have required the foundations of these early insights to reach his own.
The introduction to sequence stratigraphy is brief but clear, although it is unfortunate that sedimentary basins are described as ‘bowl-shaped depressions’. In many examples the basin results from surface loading as sediment is deposited. Thus, although it comes to have the bowl-like geometry there never was ‘a hole in the ground’ and the entire sequence may be of shallow-water deposits. That said, the descriptions of the various basin types are clear, with simple diagrams.
Chapter 2 discusses the transformation of sediment to sedimentary rock, beginning with a description of the rock cycle and the origins of grains, and discussing rounding, sorting and grain size. However, the graphic illustration of grain size in Table 2.1 gets a bit lost as size is reduced and it is not clear that this part of the diagram adds much to the numbers. It is not clear what the matrix is in Figure 2.4d, although this can be determined in the text. In Figure 2.4a quartz-arenite is misspelt. The interrelationships of this group of diagrams are not clear and question why the traditional triangular plot illustrating their continuity has been avoided.
It is disappointing to see carbonate rocks simply grouped as ‘limestones’. The weaknesses of this term were exposed in the late 1950s. Modern use (even for students) advocates classifications like that of Robert Dunham (1962), which, to some degree, mirror the divisions in siliciclastic rocks, explaining both textures and compositions. Terms, such as crinoidal limestone, travertine and oolitic limestone, do not get the reader very far. Also, dolomite rock is these days commonly referred to as dolostone. This lack of information contrasts with the clear and informative table illustrating volcaniclastic sediments.
The discussion of diagenesis is thin and perhaps over-emphasizes pressure-dissolution with disappointingly little attention to cementation, dissolution or alteration.
Chapter 3 on sedimentary structures has an unexpected emphasis, beginning with a description of ‘way-up’ using geopetal structures as the primary example. These are, perhaps, less open to dispute than other physically generated criteria, but are far less common. The excellent illustration of the Rhynie Chert is a rarity and unfortunately cherts are not mentioned among the various sediment groups. Diagram 3.3 is excellent but do we also need 3.2? The most common sedimentary structures are various kinds of cross-bedding, ripples and sand-waves (stated on p. 30!) and it, therefore, seems odd that descriptions of dynamic structures begin with less common turbidites and rare raindrop impressions. The excellent photograph, Figure 3.8, of symmetrical oscillatory ripples, is referenced in the text under ‘current ripples’ but those illustrated are probably of wave origin. The text on page 31 refers to ‘eddies’ but Figure 3.7 would have them as eddy’s! The excellent illustration of Figure 3.13 appears to be herring-bone cross-bedding, reflecting reversing tidal flows. The uppermost laminae may or may not be moulded by wave action but these structures were not formed by waves. The text following is focused on graded bedding but at this point some of the most common occurrences, in turbidites and storm deposits, are not mentioned. Although trace fossils are important, their emphasis here is disproportionate.
Chapter 4 is devoted to sedimentary environments, beginning with a discussion of source areas and environmental scale. A nice diagram (Fig. 4.2) illustrates the complex interrelationships between glacial, fluvial, lacustrine and arid systems, together with littoral, deltaic, marine shelf and deep-marine environments. There are good illustrations and photographs of alluvial fans, glaciers and lakes. However, why begin with glacial environments when they are probably the least represented in the rock record? The statement on page 41 referring to ‘an arkose (feldspar-rich sandstone) containing feldspar quartz and mica’ could surely have been put more succinctly? The excellent photograph (p. 48) of a thin section of Triassic sandstone should have appeared in Chapter 2. It illustrates rounded grains of quartz ‘cemented by quartz cement’. Apart from the repetition, the key feature in this is that the quartz cement is in optical continuity with the original grains, rather than forming independent crystals and would have been better in Chapter 2. On page 47, modern and ancient river environments are not contemporary and thus cannot form ‘a complex system’. There is a nice diagram of point-bar formation on page 48 but no mention of this in the text and no explanation.
The text also omits the fact that many of the characteristics of lagoons (pp. 50/51) depend upon tidal range. Coral patch reefs are mentioned as characteristic of lagoons but could not be so anywhere but the tropics, and stromatolites are very much less common in hypersaline lagoons that the text implies. The description of oolites (p. 52) gives the impression that the ooids consist of calcite whereas most modern ones are aragonite and compositions have alternated at periods in the past. There are, however, some nice pictures here.
Chapter 5 is devoted to fossils and sediments, but seems to lack direction. Like trace fossils earlier, there is a disproportionate focus, this time on coprolites that are not easily recognized and not particularly useful. It is noted (p. 62) that microfossils are small and examined using a microscope, yet the illustration, including other fossils to which the reader is directed (Fig. 5.1), has no scales. A number of stratigraphic terms are used here and elsewhere, but the only list of these showing their relative ages and relationships is on page 64. The illustration of a crinoid is not of Pentacrinus – this is a Jurassic species, not Carboniferous.
Chapter 6 describes the uses of sedimentary rocks. This is very brief and is essentially a list; incorporating material that might have been used in earlier chapters.
There is much to recommend this book but, perhaps, in a second edition these distractions could be addressed.