Composed of a mix of volcanic basalt, sandstone, feldspar, and granite, the Sunset Mountains are a pair of mountain ranges separated by a region of badlands known as the Sunset Vale. If they were not dwarfed by the peaks of the north and south branches of the Sunset Mountains, these badlands might even be considered mountains themselves. Their rocky ridges, canyons, gullies, and hidden, twisted valleys sport odd pillars and rock formations, apparently formed when ancient volcanic lava flows were later carved by flowing ice. Many of these rock formations have alternating tiers of sandstone and ash rock, creating a stark, contrasting ambiance of red, purple, orange, brown, and grey to black layers. Most have been smoothed by howling winds from the southeast, but some have jagged portions where pieces have broken off. Scattered patches of short, weedy scrub and thorny underbrush are common throughout the badlands, offset by the the occasional succulent (cactus-like) plant. Such plants are surprisingly resistant to fire.
Though both branches of the Sunset Mountains show signs of past volcanic activity, it is the northern branch that features the region’s only active volcano, Mount Dabryn. Though only active for a few days once every few hundred years or so, frequent plumes of smoke and steam can be seen rising from its peak. Approximately four-fifths of a mile high, its summit is truncated and contains nested craters, with an inner crater about two-thirds of a mile wide and a quarter-mile deep, and an outer crater about three-quarters of a mile wide. Featuring two parasitic cones, the larger of the which is located at the northeast of the summit, and the smaller at the southeast, during eruptions, lava tends to flow down the northeast flank, resulting in a group of broad, low-relief volcanic craters on the northeastern and southeastern sides of the volcano.
Slightly smaller than its northern neighbour, measuring approximately three-quarters of a mile high at its summit, Mount Neris, on the other hand, experiences only subterranean vulcanism. Quiescent on the surface, the region is nonetheless home to areas of intense geothermal activity deep underground, with numerous geysers, hot springs, mudpots, steam vents, fumaroles, lava pools, and similar phenomena.
Copper and iron are plentiful throughout the mountains, with many crystal veins of diamond and opal, in addition to traces of other metals, such as silver, gold, zinc, and naturally occurring electrum and orichalcum, as well as significant deposits of coal, hidden just below the surface.