Possible 1665 'plague pit' latest unearthed link to London's storied past

Archeologists work at a mass burial site suspected of containing 30 victims of the Great Plague of 1665, unearthed at Crossrail's Liverpool Street site in London.

Story highlights

• Archeologists find the remains of what are suspected to be plague victims from 1665
• At least 40 coffins were stacked into the burial site, apparently at the same time, says archeologist
• Scientists hope the remains may explain why London had no more major plague outbreaks after 1665

London (CNN)If you scratch the surface of a 2,000-year-old city like London, you frequently find clues to its past -- whether Roman, medieval or remnants of the 20th century's greatest conflict.

Three-hundred and fifty years ago, London suffered its last major outbreak of plague. As many as 100,000 people, or a fifth of its population, died as the disease swept through the city.

Now archeologists excavating a former burial ground as part of work to build a new rail link across London believe they may have found a "plague pit" -- or mass burial site -- where at least 30 victims were laid to rest.

The bodies appear to have been buried on the same day and a gravestone nearby in the Bedlam burial ground is dated 1665, adding weight to the theory that they died in the outbreak of that year.

"This mass burial, so different to the other individual burials found in the Bedlam cemetery, is very likely a reaction to a catastrophic event," said Jay Carver, lead archeologist for the Crossrail project.

"Only closer analysis will tell if this is a plague pit from the Great Plague in 1665, but we hope this gruesome but exciting find will tell us more about one of London's most notorious killers."

The burial site, uncovered last week, has at least 40 separate coffins placed in it, apparently all at the same time, Carver told CNN.

"They were stacked up, some even on their side, some orientated north-south to try and squeeze as many as possible in," he said, rather than being placed west-to-east as was customary.

The careful positioning of the coffins, and the fact they were used at all, run counter to many of the images of plague pits from the 17th century, in which corpses piled high on carts are dumped into large open graves, Carver added.

Evolution of disease

The dig is taking place in Liverpool Street in the City of London as part of work to create a new station entrance for the Crossrail link, due to start operating in 2018.

It's already revealed a wealth of historical artifacts, long buried under several feet of soil and concrete. Preliminary excavations at the Liverpool Street site in 2011 and 2012 uncovered more than 400 skeletons, according to Crossrail.

Now specialists from the Museum of London Archaeology will analyze the latest discovery in the hope of revealing whether bubonic plague or some other pestilence was the cause of death.

The number of skeletons found together may yield fresh clues, said Mike Henderson, senior osteologist at the museum. "We hope detailed osteological analysis will help determine whether these people were exposed to the Great Plague and potentially learn more about the evolution of this deadly disease."

One unsolved mystery is why this outbreak in 1665 was the last major one to afflict London.

"The particular question is, what was responsible? Actually what pathogen, what bacteria formed the Great Plague outbreak in the 17th century?" said Carver.

"It doesn't seem to come back, so something changed in the way people were living. People say the Great Fire of London in 1666 had something to do with the ending of Great Plague events, but through the scientific studies we can do these days on DNA from samples of these skeletons, we might be able to tell what pathogen is responsible for that outbreak and perhaps why it stopped."

There's no risk of people working at the grave site contracting the plague, he added, since the bacteria have long since disintegrated.

Black Death

The Yersinia pestis bacterium that is behind the plague is found mainly in rodents, particularly rats, and in the fleas that feed on them, the U.S. National Institutes of Health website says, and it's still present today.

Each year, roughly 10 to 20 people in the United States develop plague from flea or rodent bites, mostly from infected prairie dogs in rural southwestern areas, the NIH says. About one in seven of those infected dies. No person-to-person transmission has been recorded in the past 90 years.

In the 1300s, the Black Death killed an estimated 20 million to 30 million people in Europe, the NIH says. Another 12 million fell victim to the scourge in China in the mid-19th century, and smaller outbreaks have occurred elsewhere.

In total, more than 20,000 Londoners are thought to have been interred in the Bedlam burial ground, used from 1569 to at least 1738.

According to Crossrail, its excavations in London are the largest archeology project in Britain, with more than 10,000 artifacts found at more than 40 sites.