HOW THE CORAL WALLS OF A GHOST TOWN HOLD SECRETS OF THE SEA
The walls of Jazirat Al Hamra contain up to 12 million pieces of coral and each is a clue to the past, say NYUAD researchers
In the island village of Jazirat Al Hamra, people were so connected to the sea that even their homes were built of coral.
The abandoned pearling town in Ras Al Khaimah has long been admired as one of the best examples of pre-oil architecture on the Arabian Gulf.
Its walls not only tell the story of the area’s people, but the history of the sea itself. Its homes, mosques and courtyard are built from almost 12 million pieces of sun-baked coral and each is a clue to the Gulf’s marine history.
Biologists at New York University Abu Dhabi are now analysing these unusual building blocks to uncover how the coastline has changed in the past 400 years.
Jazirat Al Hamra has about 500 buildings built from coral, sand brick and cement. There are 53 kilometres of coral stone walls, averaging 2.85 metres in height and 50 centimetres thick. Unfolded, they would reach almost from the Abu Dhabi-Dubai border to Sharjah.
The average coral piece is about 800 cubic centimetres, slightly larger than a glass Vimto bottle.
“They would basically fill a national rugby pitch about a metre high, or a New York City block,” said John Burt, the marine biologist at NYUAD, who led the research.
“So they would have had to have mined about 10 hectares of reef surface.”
Pieces were recycled over the centuries. One piece dating from 1551 was found in the wall of a mosque, supporting oral histories that trace the village’s origins to the same period as the decline of the medieval port city of Julfar.
A question remains: where did the coral come from?
Oral histories on coral mining are all but non-existent. There is speculation that the Gulf did not have the reefs to support this industry and that coral was mined in the Gulf of Oman or even off the coast of East Africa.
Dr Burt believes otherwise. Coastal maps developed by the British navy from the 1820s to the early 1900s show a substantial reef once extended almost 10km along the shoreline between Jazirat Al Hamra to the Umm Al Quwain lagoon.
“One argument has been that there was no coral reef near by and we’ve shown that that was not the case,” Dr Burt said. “It was very close to the coast and potentially could have been mined on foot during low tide.”
The composition of the reefs appears to have changed little since the 1550s. To date, 11 different genera of coral have been identified from the village walls, with a variety and composition proportional to what exists today.
“Brain coral was by far the most abundant on the buildings in Jazirat Al Hamra and is still the most common on reefs in Ras Al Khaimah,” Dr Burt said. “About 40 per cent of the corals in the walls were brain coral and that basically reflects what you’ll find in reefs.”
Size ranged from fist-size blocks to great chunks of brain coral used as foundation blocks. Once mined, they were sorted by size in fresh water to kill off the organisms and dried on the beach for a year.
The porous blocks were good insulation and one of very few local building materials.
For this reason, many of the UAE’s historic buildings used coral, such as the 15th-century Al Bidiya mosque in Fujairah and Qasr Al Hosn in Abu Dhabi, part of which is believed to date from the late 18th century.
“Coral was the only hard material that people would have had,” Dr Burt said.
“You also have to recognise that this was an age long before scuba, but we have here an industry that was based on diving.”
The fossilised coral in Jazirat Al Hamra, dated by Dr Julie Retrum at the University of Mississippi, shows the town experienced a construction boom in the 18th century.
Coral mining continued into the 20th century. Samples from the Abdul Kareem House, in the village souq, date from 1886 to 1921.
Soon, cement would replace coral stone and by the 1970s, the village was largely abandoned. Seascapes, too, were transforming. The reef that extended to Umm Al Quwain has been lost to development.
“This area has been heavily developed since the 1980s, first for port construction and later for deepening of lagoons to make canals, as well as beachfront modification and nearshore land reclamation,” Dr Burt said.
“While occasional patch reefs still occur in this area, the extensive reefs that were once here no longer exist.”
On Tuesday, Dr Burt presented his findings to the Emirates Natural History Group, whose members helped with documentation of 160 village walls and 2,000 pieces of coral.
Volunteers have been essential to the project. Dr Burt credits Noura Al Mansoori, a research assistant in his lab, for developing it as a citizen science project. Their findings are now being written up.
About 40 per cent of the corals in the walls were brain coral and that basically reflects what you’ll find in reefs DR JOHN BURT NYUAD marine biologist