 The mountains are characteristic of the Great Basin 's topography of mostly parallel mountain ranges alternating with flat valleys . Oriented generally north to south , the Trout Creek Mountains consist primarily of fault blocks of basalt , which came from an ancient volcano and other vents , on top of older metamorphic rocks . The southern end of the range , however , features many granitic outcrops . As a whole , the faulted terrain is dominated by rolling hills and ridges cut by escarpments and canyons . 
