I don't know if it's the case here, but it's common practice in archeology to leave some parts of a site undisturbed. You never know how technology and techniques might improve in the future and if you dig everything up now you might destroy stuff that could have been preserved.
PaulMcIcedTea t1_ixq1eww wrote
Reply to comment by Slamdutch in Animal bones, ancient Romans’ snack food found in Colosseum by marketrent
I don't know if it's the case here, but it's common practice in archeology to leave some parts of a site undisturbed. You never know how technology and techniques might improve in the future and if you dig everything up now you might destroy stuff that could have been preserved.