The 30-centimetre-thick layer of sand-like construction material which has now hardened over a chunk of the Dwejra shoreline is likely to degrade the fossils beneath for a “very long time”, according a geologist who visited the site yesterday.

Geologist Peter Gatt concluded that the material strewn over the area, to mimic sand for the filming of a US TV series, was not regular construction aggregate as previously thought but included a mixture of silt and probably some clay. The material would not harden the way it did had there not been some other matter like clay in it, he said.

Mr Gatt was accompanied by the former assistant director at the Malta Environment and Planning Authority’s Environment Protection Directorate, Alfred Baldacchino, who this week said the ecosystem of the area had been ruined by the material.

Having visited the site, he said he was even more convinced of this position, which had been contrasted by Mepa’s environment director, Martin Seychell, who earlier this week described the area as bare rock without an ecosystem.

Strolling around the area, Mr Baldacchino came across a plant covered in dust. “This is a Darniella melitensis, the Maltese salt tree, one of the reasons for which the site was given Natura 2000 status in the first place,” he pointed out.

“The plant is endemic and, as such, is protected by Maltese law.”

A few metres away, in pools where the water is clouded with the aggregate, some small crustaceans survived, flitting round the water.

“Looking around at the parts which have just been cleaned, there are also indications there were some very adequate rock pools... where the whole ecological niche was disrupted and eliminated.

“If an appropriate assessment had been done, which was necessary for such a development, one could have easily indicated all these things,” Mr Baldacchino said.

Mepa had admitted that no impact assessment was done and a review is being carried out to establish whether the permit procedure for filming in sensitive areas should be changed.

However, the regulator has insisted that had the producers followed the conditions it set out in the permit the incident would have been avoided.

Whatever the case, the experts who visited the site at the request of The Times said the damage was likely to have long term consequences.

“This is a very important site which has been partly ruined,” Mr Gatt insisted, stressing that, scientifically-speaking, Dwejra “is an exceptional area, not only in Malta, but also in Europe”.

The fact that the material has hardened over the fossil-rich area means the fossils would be less visible than they were previously.

Moreover, the construction material would contaminate the area, hampering scientific studies.

“Geologists usually take samples of rocks... to date them and to get to know the environments in the past. So when you have extraneous material such as this sand or soil, it’s a source of contamination. And even though the site is cleaned up, a good ­percentage will remain here and will contaminate the surface of this exceptional area,” Mr Gatt said.