The dig is the latest in a series of excavations in and around the Yard. Some of the others, including the most recent, a dig behind Wadsworth House completed in June, have also turned up artifacts of student life.

But according to Mandryk--who estimated that excavations will be finished today--the Holden Chapel site could give archaeologists the first clear look at academic life at Harvard in the early 19th century.

The discoveries are also expected to delay the building's reopening.

Renovations of the chapel basement were due to be complete before classes started in September, but Michael N. Lichten, director of the Office of Physical Resources in the Faculty of Arts and Sciences, said the dig, could set the renovations back at least three weeks.

The workers will not even be allowed on the site until further environmental studies are completed, due to the presence of arsenic.

"Now that they have determined that there is a certain level of risk access," Mandryk said, the site "is going to be limited to trained personnel.

Construction officials said the length of the delay will be determined by the amount of time it takes before construction workers can get back onto the site.