Rostrally, the isthmus demarcates the boundary with the midbrain. This watershed demarcates the boundary line between the Harifal and Sherani tribes. The Los Lobos thrust fault complex demarcates the western boundary of the field. Its long northern boundary demarcates part of Cambodia's international border with Thailand. In the south, a forest roads demarcates the boundary. The Columbia River demarcates the county's north, south, and east boundaries. Ontario Street (two blocks west of Main Street) demarcates the boundary for this prefix. The transition between these sources is important as it demarcates the foregut from the midgut. The San Andreas Fault, which demarcates this boundary, is about 40 miles away. Sufism demarcates the physical body from the Nasma. It demarcates the inferior border of the inguinal triangle. This structure demarcates the superior border of the femoral triangle. A "cement line" demarcates articular calcified cartilage from subchondral bones. The freight-only Bay Ridge Branch demarcates the western border of East New York. It is located on the River Barrow, which demarcates the border between the two counties.