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Dinosaurs at Crystal Palace Park
Structural engineer Edward Morton finds himself investigating the authentic way of conserving a pterodactyl and reconstructing a limestone cliff.

Pterodactyls and Teleosaurus - the Pterodactyls are new fibreglass models based on historic photographs whilst the Teleosaurus is the original repaired statue

The great thing about being a conservation engineer is that you must have a good all round understanding of inter-related matters such as architecture, archaeology, monuments, and materials.

For me the sheer variety of projects has included castiron fountains. piers, timber viaducts, a tunnel for a model railway enthusiast through his rear wall (much to the concern of his wife), stunt men jumping off castle walls into moats, hanging of tapestries at the Guildhall in London, and dinosaurs.

My introduction to the dinosaurs at Crystal Palace Park came in 1995, when the London Borough of Bromley asked us to set out our experience with dealing with statues of dinosaurs and associated geological illustrations. Being honest, I was not able to give any examples of other statures of dinosaurs that we had repaired, but I was able to point to a number of garden and park structures we had worked on.

The 29 remaining statues and illustrations were completed in 1854 by the sculptor Benjamin Waterhouse Hawkins, under the guidance of the famous palaeontologist Sir Richard Owen. Their importance lies in their being the first attempt in the world to interpret what full-scale prehistoric animals would have looked like.

They were part of a new Victorian theme park which included the re-erection by joseph Paxton of the Hyde Park Crystal Palace in an altered and extended form at the top of the park, along with other attractions including an elaborate fountain system.

Hawkins' scheme was curtailed due to financial difficulties of the park project. The missing elements were a considerable number of mammals from the tertiary and quaternary epochs and their associated geology. These included 15 other species such as a mammoth, a glyptodon (giant armadillo), a mastodon and others.

The financial difficulties at the time were reflected in the construction of the statues, whose materials ranged from a form of concrete with tiles set in a very durable mortar, to cast-iron drainpipes, wroughtiron rods and bands, carved stonework, and cast lead with sculpted detail. Later repairs included the use of scaffold poles, mortar repairs and even plasticine with a thin resin skin, and fibreglass replacement parts.

A pair of Iguanadons (the horn on the nose of the fossilised creature on which this model was based was later found to be its thumb). In the background are the two repaired Pterodacty ls with the re-constru cted chalk cliff.
The whole display sets out a time trail through the epochs. It shows the various species of dinosaur set in their correct geological context, related to where their bones were found. The exhibits greatly increased the general public's interest in palaeontology. It was not long before new discoveries were made which effectively outdated Hawkins' creations, leading to a decline in their public appreciation. Today their importance has been recognised by their listing. The statues and illustrations represent a snapshot of contemporary thinking on such matters.

A 1996 feasibility study showed that other than ad hoc repairs and maintenance no co-ordinated and researched work has been undertaken since the statues have been constructed. The geological illustrations had been largely unknown until a few years previously, when Peter Doyle had highlighted their significance in relation to the overall display, and the great skill and ingenuity used in forming them as accurate representations of the geology of the British Isles and the associated importance to the wealth of the nation. The display included a two-thirds reconstruction of a lead mine, including crystal grottos with stalactites and stalagmites.

Several elements of the original were found to be missing, as historic photographs showed. These included several statues, and illustrations of things such as the chalk cliffs adjacent to the pterodactyls. A mountain limestone cliff had been blown up in the 1960s for which no photographic evidence was found, although much historical reference material was available and there was some local knowledge from verbal descriptions.

Hylaeosaurus - the head is actually a fibreglass replica of the original which is currently in front of the Tourist Information Office
The feasibility study outlined the scope of repairs necessary. The work was programmed in three phases: the repair of the existing, the reconstruction of the known missing elements, and the completion of the original scheme. The latter would be based on historic reference material, such as a letter from Hawkins to Owen in 1855 describing how he had intended to complete the display, although obviously this would be inevitably partly conjectural.

An application by Bromley Council to the Heritage Lottery Fund was successful, and additional funding was obtained through the Crystal Palace Partnership (SRB funding) and from other sources. During the detailed design period, Hirst Conservation carried out extensive paint sampling work and trial cleaning. Holden Conservation carried out repairs and painting. Mortar testing identified that every sample varied in its make up, confirming that Hawkins was limited in resources. The paint analysis (over 430 samples) identified in areas up to 24 layers and gave some clues to possible original paint schemes.

Megalosaurus undergoing paint stripping
The specifications and schedules were drawn together with much assistance from Peter Doyle, particularly in relation to the geological illustrations. The conservation package was let to Eura Conservation working with Holden Conservation.

Trips with Peter Doyle to quarries around Derbyshire to identify the best match to the missing mountain limestone were highlights (except for the damage to my car suspension). The supply came from a quarry called 'Once a Week Quarry' because it was only open once a week. Perhaps one of the biggest challenges was the reconstruction of the limestone cliff. Early excavation and opening up of the original area showed the lead mine to be in poor structural condition and unsafe to work in. We suspected that this related to the removal of the buttressing effect of the original cliff, tree root action and a possible increase in the amount of soil over the top of the structure.

The reconstructed limestone cliff
Excavations identified the original foundation of the cliff.The initial exercise, once Peter Doyle had identified the correct face and stratographical orientation of the stones, involved piecing together 130 polystyrene blocks, cut to match approximately the rough-cut blocks received from the quarry, to enable a model of the proposed limestone cliff to be built. Building this new structure to match a natural cliff was considerably more difficult. The blocks generally weighed more than one tonne and a quagmire of mud had developed through the winter months.

Although public access has not been allowed to the lead mine, for health and safety reasons, this can be opened up relatively easily in the future if funding becomes available. Where new internal walls were constructed, with no evidence of the original, we felt it appropriate to use rough render, clearly identifying this as new work.

The lead-sculpted models were found to be solid, rather than skin on a solid core, as had been assumed. They were fixed to the concrete bodies with iron dowels which had inevitably corroded, causing the leadwork to split. Several of the legs were recast, where possible keeping the intricately carved details such as the hoofs.

The missing statues were re-formed in fibreglass by Fredrica Banks Ltd, with clay models initially carved to allow comments from Peter Doyle and others. Although the fibreglass will not have the life of other statues, the moulds have been retained for future recasting.

The completion of the original intentions of Waterhouse Hawkins' scheme is to be considered by Bromley.

Edward Morton is managing director of the Morton Partnership
CONTEXT 75 : JULY 2002