Situated on the northwestern portion of Seward Peninsula, it was included in the Agiapuk River mining district.
The Mary River has a length of about 20 miles (32 km) and flows into the upper end of Imuruk Basin.
Between the forks of the river there is a broad, flat-topped ridge, with an elevation of 700 feet (210 m), which is partly covered with washed gravel.
These buttes are composed of white crystalline limestone, whose bedding is obscured by jointing and cleavage.
Except for these buttes, the bed rock, as indicated by fragments found on the surface, consists of calcareous mica schists.