The Golden fault is a N20°W-trending, west-dipping, high-angle reverse fault. This complex fault, more than 30 km long and as much as 1,000 m wide, is a part of the structural zone that bounds the east flank of the Front Range, Colorado. Recent trench excavations through a part of the fault zone near Golden reveal a minimum of two periods of movement with a total of 5.5 m of vertical displacement since the Yarmouth(?) interglacial period. One movement postdates a Yarmouth(?) paleosol developed on colluvium that overlies Kansan(?) outwash gravel but predates deposition of a 0.6- to 0.7-m.y.-old volcanic ash. A second movement postdates deposition of the volcanic ash and overlying colluvium, but is believed to predate development of the surface soil of Sangamon(?) age.