Inora Newsletter #46
A SHAFT OF LIGHT ON THE STUDY OF PARIETAL ART:
DISCOVERIES AT GOUY
The use of paint at Gouy
The remains of red paint, in the first gallery suggested a very limited use of paint at Gouy. To know more, a method capable of outlining the contours of these paintings -if any- was essential. A large number of unsuccessful attempts (Aujoulat 1987; Vertut 1979) were necessary before it became possible to obtain a satisfactory solution.
The most appropriate method was found in a different domain from the means normally used for the study of parietal art, after several years of investigation. It is the use, originally for biological purposes, of a means of lighting -a fluorescent tube used for vegetation- at present used in aquaria. Highly effective, it revealed at Gouy a painted line some 1.30m long and dark red as soon as it was first used.
And yet, no trace of paint had been known at this precise spot. The red line had never been noticed nor photographed before. This discovery suggested that other painted elements might exist in the cave. Future study confirmed this hunch. Other data (very “readable”) has also been revealed by the same lighting system.
The method showed itself extremely useful when applied to decorated walls. The reds (very vivid) cannot be missed in any survey.
With this system three types of paintings up to now unnoticed were shown. The one already known corresponded in fact to two different paintings (n°4 and 5):
painting n°1 red (dark brick red),
painting n°2 red ( projected red ochre),
painting n°3 orange (orangey yellow ochre),
painting n°4 red (fluorescent red ochre) same colour and tonality as n°5,
painting n°5 (neutral red ochre) same colour and tonality as n°4.
(L= 130cm, w= 0.5cm) (27d-47d) red n°1: today in eight segments (Fig. 1-4), the line was probably made with a finger dipped in paint or directly with a thick block of viscous colouring matter. The left extremity curves as though for the line of an animal’s back (rump, backbone: Fig. 3-4).
The coloured deposits left on the bumps on the wall show its upward slope (from left to right: Fig. 2). Until now it had not been possible to see it, even though its site had been copied and photographed from all angles, however purely concerning the engravings (Fig. 1). In old photos and publications it had never been noticed (Martin 1973: 156). No other point where this paint was used is at present known, but several square metres of wall were destroyed in road-making between the river Seine and the cave. The ancient entrance and a part of one gallery thus disappeared before revealing their contents. This irrecoverable loss must be taken into account in all studies of the Gouy Cave.
The probable hypothesis is that of a magico-religious act on the decorated wall: the deposit by spraying of a coloured substance during “ceremonies”.
(L= 10cm, H= 12cm) (53g) red n°3: this sign (Fig. 8-9) is in the form of an “n” or an “h” with its “legs” coming together towards the base: does this represent the legs, belly and back of an animal or a painted triangular sign…? The shape does not seem to be closed at the base; its study needs to be completed in detail (as for all the surrounding painted remains associated with it).
Fluorescent red paint
Red n°4: under UV lighting this painting gives a strongly saturated rose-red luminosity. Light emission (in the visible spectrum), is provoked by exciting ultraviolet light. This luminosity was seen for the first time by the author together with the late Alexander Marshack when he came to Gouy with a Wood Lamp working with a battery.
Using similar material, the two red paintings could finally be differentiated, following this memorable visit, but this happened much later when financial conditions became more favourable:
red n°4 was more extensively used than red n°5;
red n°4 was exclusively used for the contours of the shapes, lines and flat tints;
superficial scaling only concerns surfaces painted with red n°4;
certain areas painted with this red could correspond to simple colour washes.
Luminescent materials commonly found and described underground are generally limited to calcite and aragonite (Aujoulat 1987). They appear in a sparkling white that cannot be confused with colour emitted by red n°4. Even so, “red and orangey-red” are mentioned as the fluorescent colour of certain forms of the so-called Arizona calcite (in California) and from Franklin (in New Jersey) (Eastman Kodak 1972), in using shortwave UV, contrary to Gouy, where only a very long wave UV source of lighting is used.
No other publication mentions a phenomenon similar to that observed at Gouy. The painted motifs usually appear under the rays we used as black without any light emission. At Gouy, the rose-red photo-luminosity could be recorded on “daylight” type colour photographic film
There could be multiple reasons for this light emission. It could be the incorporation of particular substances to the paint (voluntarily or otherwise) or to the presence of certain micro-organisms (certain lichens?). But in the latter case, it would have been necessary, if this were so at Gouy, for the micro-organisms to have persisted only on the painted surfaces without ever prospering outside them (Fig. 12).
Pigment analysis is then essential to the study (Martin 2004). A request for the authorisation of a research programme was consequently made. A study project for the Gouy pigments was submitted to the French Ministry of Culture. Firstly, a series of exchanges started in 1996 with the CNRS researcher Bernard Guineau “The Study of Pigments, History and Archaeology” (Centre Ernest Babelon, Orleans) with this objective.
Red n°5, neutral: under UV light, this paint appears from black to grey, following its pigment concentration, never emitting any luminosity. Because of this, it is very difficult to localise with the Wood Lamp on walls like these where all sorts of greys mingle.
Its use seems very limited, contrary to red n°4:
red dots and smears seem to have this paint reserved for them;
unlike the n°4 paint, it never suffered from scaling.
The empirical distinction between the two paints seems confirmed. This is suggested by the preliminary tests using the variable pressure scanning electron microscope (Eric Beucher “Analyses & Surface”, Louviers, Eure).
The painted walls
The painted motifs are exclusively localised in the upper section (left wall of the first gallery).
The red n°4 paint is in both the upper and lower sections.
The red paint n°5 is only in the lower section.
The n°1 red paint which was only used for painted lines spreads into both sections (right wall).
Gouy had always been considered as an “engraved cave”, and until now only had one technique (engraving) in its inventory.
At the beginning of a more detailed and very promising study, this time including paintings and engravings, its corpus is now increased by four new motifs.
Other new data
The contribution of the horticultural fluorescent tube is not only limited to the spectacular discoveries described. Under this light a mass of new information now appears (cf. table), while with a UV lamp, photography with filters, special film and image treatment, the data is gathered separately.
These usual methods still have their place. However, the horticulturists’ fluorescent tube enables remarkable visual observations such as those below without eye-strain, contrary to the Wood lamp, whose rays rapidly fatigue the eyes.
The concentration of red pigments can easily be evaluated once the painting is lit.
Painting and natural oxidations can easily be separated one from the others.
The rock wall is distinguished from all the other elements on its surface.
Patina is shown and its details can be very exactly noted.
Calcite surfaces are easily localised when before unknown.
Algae and lichen are clearly marked, including those previously unsuspected.
Bone and bone fragments on the walls and floor, unsuspected before, are now revealed.
Almost invisible fossils on the rock wall are clearly localised.
Flints (apparently similar) show their different aspects: colours, patina, breaks.
Shocks to the walls and ancient surfaces (destroyed) can be detailed.
Historic period scrapes and scratches can be recognised for what they are.
Details concerning the lighting
As the eye adapts little by little to a certain level of light, colour perception progressively develops. Thus with the dominant violet-rose, over-present and disturbing at the beginning, the light emission rapidly fades with chromatic adaptation.
This facility enables a genuinely white surface, first appearing coloured rose-violet, to be seen as really white. Obviously, photography does not benefit from this adaptation. In these conditions, the 80 B filter gives two convenient correction possibilities:
on the lens (inconvenience: it involves an exposure correction);
on the optical projector (correct reproduction when showing the slide).
With digital photography the correction is automatically made. The red paint revealed by the lighting is efficiently restored and safeguarded while the rose-violet light pollution is eliminated.
Generally, with the horticulturists’ fluorescent tube, it is impossible to miss even the most infinitesimal red present on the wall. Thus, a very small unrecorded coloured element jumps to the eye, when up to this point it had been forgotten, unnoticed and not noted (if even barely seen). This method of lighting can now be added then to the range of other methods of studying decorated caves. The heat produced by the tube is very low. The stability of a fragile environment is preserved, as always, by spacing out study sessions.
The system can be used in other fields: in portable art; to study cave floors; during excavations, even in the open air; for reading sections; in rock art (at night).
Finding the correct material
There are two fluorescent tubes for use in aquaria, in appearance an identical white (with no indication of difference) on the market. Only one gives the maximum data, but on purchase it is impossible to know which of the two is on offer.
By chance it has been possible to make a distinction (after purchase): in the dark without connecting them to electricity they should be illuminated by UV light (black light):
the one for our purpose becomes completely and uniformly coloured (giving off a powerful magenta red light);
the other, at present the most widespread, only gives off a light pale blue. The manufacturer (SLI SYLVANIA) has unfortunately until now not wished to help solve the problem posed.
Elements involved in the continuation of research
Complementary research programmes to those planned could be developed, particularly concerning the following points:
the updating of photographic archives and copies with the aid of existing technical means;
noting the different pigments used;
detecting the composition of the paintings;
the study of superimpositions: engravings/paintings and paintings/engravings;
the detection of the presence (or not) of elements enabling direct dating;
comparative analyses of samples of mineral deposits near the cave, in order to determine the origin of the Gouy paint (perhaps local).
Finally, links between the decorated wall and material from the floor might be shown from:
a backed point, ochred (red);
a blade whose base has traces of red ochre;
the ochred interior of a perforation in a cervid tooth (an element of adornment).
We also need to consider the red signs of the grotte du Renard at Orival in such a study. A general survey of the two caves needs to be carried out at the same time (Martin 2001: 215); it is in this sense that my official request for the two sites was formulated on 27 August 1998.
The recent discoveries would not have taken place without the decision to study, in the first chamber, the walls near the ceiling vault and the paint remains there. The discovery of a “new cave” was the happy outcome of the preliminary work. There is now a new picture of the whole cave, which means that the field for investigation is also considerably enlarged.
At the present stage of research it seems more and more probable that the little cave of Gouy was visited over a relatively long period (over several phases of engraving and painting). This, in particular, seems to be what the parietal art suggests, with three distinct graphic groupings (Martin 2005b). An unusual group, made up of very faint incisions, engraved close to the ceiling vault of this same gallery, is of particular interest in this regard. With elements more usually considered as mobiliary, it provides material for a consideration of the passage from the Magdalenian to the Azilian (Martin 1998).
With the useful results of the lighting system described above it is to be hoped that it can show itself equally useful elsewhere. While awaiting the day when new studies at Gouy are officially authorised it should be remembered that only permanent access to the site (as before) will enable completion of the research started as well as the necessary monograph.
101 Sente aux Dames 76520 Gouy. France firstname.lastname@example.org
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