Gold Mountain (on the south) is composed mainly of marine basalt flows and related volcaniclastic rocks (such as breccias and sedimentary interbeds) of the Crescent Formation, part of the Siletzia terrane that formed around 50 million years ago (early Eocene).

Strands of the Seattle Fault, which east of here trend nearly due west-east, appear to turn to the southwest in the vicinity of Green Mountain.

[12] In 1895 it was reported that ore of three to five percent tin had been found in this vicinity, and the Cook Kitchen Mining Company had been incorporated with $2,000,000 of capital to develop the claim.

[16] The only other known metalliferous mining claim in all of Kitsap county – the "Elmer Nelson Property" – is on the south flank of Green Mountain, just above Gold Creek.

[20] The hills have long been identified as an important watershed for Bremerton and the surrounding area, as the Kitsap Peninsula has no major lakes or rivers, no access to mountain reservoirs fed by snowmelt, and the groundwater is limited in quantity and quality.

[25][26][27] The Union River, which rises in the hills, was impounded in a deep valley on the eastern flank of Gold Mountain by Casad Dam, completed in 1957.

[32] The Mountaineers maintain an outdoor theatre, Kitsap Forest Theater, in their 386-acre (156 ha) Rhododendron Preserve on the north side of the hills.

[34] There is one 386-acre (156 ha) former shooting range, Camp Wesley Harris, owned by the U.S. Navy, and the private Kitsap Rifle & Revolver Club.