Updated: Sep 27, 2021
Flint, Solid and void; an inversion at the heart of Henry Moore’s exploration of the relationship between positive and negative space.
Among the many ways in which Henry Moore’s work have entered general awareness lie two points; the relationship between the solid body and the void, and the influence on his work of the natural forms of stones, particularly flints. The first can be found in popular culture from mass-produced decorative sculpture to graffiti, while the second is readily picked up by students of art history and those interested in Moore’s working processes. The influence of the first on sculpture since the 1930s can be seen in Tara Contractor’s introduction to Body and Void , an exhibition at The Henry Moore Foundation, which states that ‘Moore’s interest in void, or opened volume, pervades contemporary sculpture.’
A quick google search reveals a broad range of studies of the theme – ‘Both the city of Siena and More's "Reclining Figure" sculptures are physical structures that incorporate voids as a major part of their body, so I chose to study the relationship between what is solid and what is void in these objects and their relationship.’
The title of Rudolf Arnheim’s 1948 essay, ‘The Holes of Henry Moore: On the Function of Space in Sculpture’.
Moore’s own ‘Some Notes on Space and Form in Sculpture’ (1970) ‘At one time the holes in my sculpture were made for their own sakes. Because I was trying to become conscious of space in the sculpture, I made the hole have a shape in its own right. The solid body was encroached upon, eaten into and sometimes the form was only the shell holding the hole.
Recently I have attempted to make the forms and the spaces – (not holes) – inseparable, neither being more important than the other.’
The key aspect of this relationship between solid and void is that they are interdependent, neither seen as positive or negative, but defining form together; the space has/is form as much as the solid has/is form.
Moore’s drawings of flints show how important an influence on his work this geological material[PD1] was, and the Henry Moore Foundation collection includes both flints and drawings of flints, e.g. Flint for Maquette for Spindle Piece (LH 591), Flint Torso Figure HMF 80(88).
The highlight of a recent visit to the Henry Moore Foundation was the viewing of the vast number of maquettes and source items held in one of the studios on the site. Strongly featuring among them are a number of flints, including ones with a prominent hole, which sit on the windowsill and the desk.
If there is any awareness amongst the studies of Moore’s work, including his own, of how flints come to be formed, it is not at all prominent. And yet it is spectacularly important to the nature of the interdependence of solid and space in the form of the flint, and thus has implications towards Moore’s work, in terms of the interchangeability of solid and void. Flint may be formed in a number of ways, involving the precipitation and concretion of silica, though there is still considerable ambiguity surrounding this. One of the most prominent explanations involves the silica filling spaces left by animals or the passages in the chalk they created, or by being precipitated in void spaces left by dissolution of the chalk itself. A few examples:
1. In a response to a question posed by Angus Stephen in October 2009, ‘How is flint formed in Chalk on the southern coast of England?
The reply given by Amanda Lane (Chair of Solent Regional group of the Geological Society) stated that
‘Flint is a microcrystalline rock made of silica and is considered to have begun forming soon after the deposition of Chalk. The silica replaces the original Chalk carbonate grain by grain. The carbonate has to be dissolved with silica precipitated in its place.
As Chalk is an alkaline rock an acid has to be generated to dissolve the Chalk in order to enable the silica to precipitate. Bacterial activity in the sediment within the seabed generates hydrogen sulphide which, when migrating towards the seabed/seawater interface, meets dissolved oxygen migrating down in the sediment.
Where the dissolved oxygen and hydrogen sulphide meet, acidic conditions are generated, carbonate is dissolved and silica precipitated to form flint. The silica that formed the flint derives from silica fixed in the skeletal structure of many marine organisms.’
There are various explanations for the shape of the flints formed, but this is given by the website Discovering Fossils
Flints are concretions that grew within the sediment after its deposition by the precipitation of silica; filling burrows/cavities and enveloping the remains of marine creatures, before dehydrating and hardening into the microscopic quartz crystals which constitute flint.
2. Or by David Bone of West Sussex Geology
The chalk sea bed is deeply burrowed by many different organisms, such as shells, echinoids and worms etc. Some of these burrows are quite deep or branching, or have open living spaces. The burrows fill with sediment after the organism has died, this is slightly different material from the sediment around it. These filled burrows act as preferential pathways (conduits) for the chemical reactions to occur. Flint formed within these old burrows often has a nodular shape which reflects the whole, or part of, overgrown remnants of such burrow systems.
3. Or from the website for Saffron Walden Museum (a few miles from the Henry Moore studio site)
As it [chalk] compacted, it squeezed out the seawater containing dissolved quartz, or silica (which comes from the skeletons of tiny sponges, a very simple animal). This silica was pushed out into gaps, cracks and burrows in the chalky mud to form nodules or layers of flint. These flints have a white outer layer (cortex), and are black inside. They can come in very complicated, bulging shapes, or with spikes, holes and cavities.
All of these processes indicate that the solid aspect of a flint occupies either what was once an animal’s skeleton, or a void left behind by the movement of an organism, and the aspect of a flint that appears as a cavity, whether piercing or just intruding, was once solid. Thus the solid flint is formed by the crystallization of silica within a space that was previously either an animal or void. The flints that fascinated Moore appear to have been those created by the filling of burrows rather than the replacement of the physical skeletons of animals. Effectively he was fascinated by the void-made-solid.
Does this alter how we look at Moore’s work? Perhaps, insofar as we might think of art telling us what the world is like, not just what it looks like; or linking art to science; or that all forms of knowing the world can be interconnected. Moore could not have known of the void-filling theory, since though the idea that silica replaced a creature was proposed in 1920 - the ‘filling of tests [shelled molluscs] or parts of Sea Urchins and brachiopods by silica gel (Brydone, 1920)’ - the idea of void-filling is comparatively recent – ‘Madsen & Stemmerik (2010) added void filling and phase transformation to the silica-calcite replacement theory as the pre-requisite for flint formation’.
We may surmise that the conceptual relationship would have delighted Moore, but even though that remains fantasy, the findings of scientific research add conceptually to our understanding of space and form as it was pushed forward by Moore’s investigations.
Julian Walker, 2021. All websites accessed 10,9,21. Photograph by Anne Eggebert. With thanks to Peter Doyle.
 published 13 May 2014 https://www.royalacademy.org.uk/article/body-and-void-at-the-henry-moore Master of Architecture thesis Tali Cohen, B.Arch, Kansas State University, 1994 https://core.ac.uk/download/pdf/84601052.pdf  ‘The Journal of Aesthetics and Art Criticism’ Vol. 7, No. 1 (Sep., 1948) https://www.jstor.org/stable/426264 Henry Moore, Some Notes of Space and Form in Sculpture, 1970, in Henry Moore: Sculptural Process and Public Identity, Tate Research Publication, 2015, https://www.tate.org.uk/art/research-publications/henry-moore/henry-moore-some-notes-of-space-and-form-in-sculpture-r1145426, accessed 10 September 2021.  See Mohammed Musa Aliyu (2016) The Origin and Properties of Flint in the Upper Cretaceous Chalk. Unpublished PhD Thesis, University of Leeds; this thesis reviews a number of origins. http://www.discoveringfossils.co.uk/flint_formation_fossils.htm http://snpr.southdowns.gov.uk/files/additions/For%20how%20flint%20is%20formed.htm https://saffronwaldenmuseum.swmuseumsoc.org.uk/identification-flint-fossil-sponge/ Brydone, R. M. (1920). The origin of flint. Geological magazine, 57(09), 401-404.  Madsen, H. B., Stemmerik, L., & Surlyk, F. (2010). Diagenesis of silica-rich mound- bedded chalk, the Coniacian Arnager Limestone, Denmark. Sedimentary Geology, 223(1), 51-60.  Both quotes from The Origin and Properties of Flint in the Upper Cretaceous Chalk, Mohammed Musa Aliyu, Doctor of Philosophy thesis, University of Leeds, 2016 pp31-2, https://core.ac.uk/download/pdf/42606033.pdf