Archaeologists at the Petrified Forest National Park in the southwestern U.S. have discovered an ancient village that is unique for its size.

Park officials say 50 to 70 pit houses are organized in rings on about 66 acres (26 hectares). One village found last summer spanned about 14 acres (6 hectares).

Archaeologists say the pit houses were built more than 1,000 years ago in the Basketmaker period. They say that's when groups of people started settling together in villages.

The pit houses made of stone slabs were found in sand dunes. Traces of stone tools and early ceramics also were found nearby.

The discoveries are part of three-year, grant-funded project to survey 45,000 acres (18,211 hectares) of land that has been added to the Arizona park since 2004. The villages were found on the eastern portion of that land.

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