Probably named for Southgate Farm, eastern St. Croix, VI. Occurs as a small intrusion about 0.75 mi wide in center of East End Range; length unknown as it is covered by alluvium at either end. A small intrusion to its east at Pull Point is probably the same rock. Fresh exposures are rare. Consists of diorite with accessory augite, magnetite, and apatite, and essential hornblende and plagioclase. Hornblende crystals up to 10 mm long observed in body at Pull Point. Intrusion is discordant, lacks foliation, and is intruded into unmetamorphosed country rock. Age is not specifically given, but author notes that Maastrichtian to Oligocene time was characterized by low-grade metamorphism, folding, intrusion of igneous rocks, faulting, uplift, and formation of a wave-cut terrace. Report contains geologic map.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Referred to as Southgate pluton in table 1. A K-Ar date of 66.0 +/-3.2 Ma indicates an age straddling the Mesozoic-Cenozoic boundary. Data from Van Hinte (1976) as reported in Speed and others (1979).

Source: GNU records (USGS DDS-6; Reston GNULEX).

Author follows usage of Whetten (1966) for the geologic units on St. Croix, VI. They include (ascending) the Late Cretaceous Mount Eagle Group, which consists of the Caledonia Formation, Allandale Formation, Cane Valley Formation (and its East End Member), and Judith Fancy Formation; Late Cretaceous Southgate Diorite and Fountain Gabbro intrusions; and Tertiary Jealousy Formation (early Eocene to middle Miocene) and Kingshill Marl (late Miocene, based on Gill, 1990).

Source: GNU records (USGS DDS-6; Reston GNULEX).