The title is correct – this is the ‘essential guide’ to both the physical and spiritual geography of the Avebury area. It is a travel guide, lightweight enough to take into the field; a quasi-guidebook, clear enough to sit indoors and interrogate the 400 detailed photographs; finally, a contributory text adding new written, but, more especially, visual, data to the debates on the shapes and meaning of the sarsen stones and the siting of them, but perhaps not their geological origin.

The guide gives highly detailed descriptions of the major sites including Windmill Hill, West Kennett Long Barrow (WKLB), Avebury, West Kennet Avenue (WKA), The Sanctuary, Silbury Hill and the West Kennett Palisades. Marshall’s descriptions and photographs of the visually challenged Windmill Hill, The Sanctuary and West Kennett Palisades are possibly as useful as physically visiting them. This is, of course, not so for the other sites and naturally, as befits the title, much of the book is dedicated to Avebury and its offshoot avenues. For each site no stone is neglected, all take their turn in the flashlight and, in addition, for WKLB, Avebury and WKA, the stones are shown alongside one another and to scale, en-sepiaed like the reluctant mugshots of the Victorian underclass.

But intangibles like sound and sight-lines are also included. Marshall, an ex-professional musician/composer, discusses his experiments with a bull roarer about and within WKLB. Less convincing or harmonious is the popping of balloons in a chipboard reconstruction of the stones at Longstones Cove. Indeed, a photograph of four, large, wooden panels is a jangling (and somehow, intrusively modern), dissonant image. Although less fantastical than their use for trapping sunlight (as suggested for ‘the other place’ in Wessex and by others), open air stone circles, large or small, would seem poorly designed for impressive acoustic displays.

Photographs of sight-lines towards, away from, or between the sites are skilfully shown. In such a geomorphologically modest landscape, celestial / calendrical sight-lines would have been a challenge to determine, just as they are for Marshall to demonstrate, but the book has them aplenty and they repay careful examination. The relationship between WKLB and sunlight at the equinoxes (pp 49–51) is among the best examples of what can be shown.

The book starts with the essential elements of (and for) the landscape, namely stone, water and, less obviously, trees (yews and willows). There are pages of photos of different sarsen drifts, including one that wittily combines sheep camouflaged among the stones, ‘greywethers’ all. Descriptions and discussion of the geological origins of sarsen (an enigmatic, silicified sand / sandstone with a number of disputed origins) and its characteristics rightly run throughout the book. There are some misconceptions (‘liquid silica’ is used instead of dissolved silica), the time required for silicification and the origin of dark brown ‘rock varnish’ and of some of the small circular holes (‘eddies’) in the sarsens and the importance of the body colour of the sarsens are speculative or are, perhaps, overemphasised, but there are many clear photographs of these attributes, allowing an informed reader to decide their validity.

But for Marshall it is the local water table, appearing as moving water, notably spring water and especially (slightly) warm spring water, that is the key to the landscape (and his interest), and he makes a convincing visual argument that the rivers Kennet, Oslip and Winterbourne that run next to, or even through, many of the sites are their prime urge and certainly a reason for the digging of their very deep ditches. A moated Silbury Hill is compelling in its isolation.

Although the text is accompanied/augmented by an extensive online site, this remains an old-style, interactive book (the attentive reader and the pages). The majority of the book pictorially describes West Kennett Long Barrow (sixteen pages), Avebury and its associated avenues (forty-six pages), Silbury Hill (eleven pages) and The Sanctuary (eight pages) among other sites, all with a complementary, clear, informative text. Truly, here, less is more and the sparseness compels the reader to interrogate and challenge the photographs. Perhaps one of Marshall’s most lasting gifts is to show the evidence, or rather lack of it, for the notion of elongated male and equant female stones and their couplings within circles (p 68) and avenues (p 96). Seeing them side by side and paired must lay this recent myth to rest. Indeed, it is telling that the best example of a visually ‘coupled’ pair, namely Adam and Eve – the latter, the lone survivor of the Beckhampton Avenue – show a very tall, slim Eve and a very heavy, squat Adam (perhaps an extreme case of sex reversal?).

Marshall’s whimsical love of composite plates, lichens on sarsens, wild flowers (representative of plant remains in Silbury Hill) and stone buildings in Avebury, although unnecessary, progressively surprise, enrich and delight. However, it is the landscape photographs that leave the longest lasting impressions. Although largely steering away from the New Age mystical, there are suggestions towards the end of the book, many these photographs, especially the snowy wintertime ones with a hint of springs, that evoke earlier, elemental, possibly collectively shared folk emotions, so that he seems to take Robert Frost’s words for his own:

Exactly. This is an important record, but better, it is wonderful, wonderful book.