Sinkhole in Ronan Park found to be caused by collapsed historic well By Matt Berg Globe Correspondent,Updated December 10, 2020, 5:56 p.m. Email to a Friend A large sinkhole was discovered in Ronan Park on Sunday.Erin Clark/Globe Staff Four days after a mysterious sinkhole was discovered in a Dorchester park, city archeologists revealed Thursday that the hole formed after the ground collapsed above a cobblestone well built more than a century ago. On Sunday, the sinkhole in Ronan Park was reported to the police, who secured the area. Later that day, Bostonâs archaeologist, Joe Bagley, got a call from city officials.