Sunlight Creek flows northeastward into Clarks Fork River in the northern Absaroka Mountains of northwest Wyoming. Two periods of glaciation are here recognized from the degree of erosion of the moraines. An early ice sheet from the Beartooth Plateau to the north invaded Clarks Fork Valley; but, being unable to move eastward through the Clarks Fork Canyon to the plains as rapidly as ice filled the valley, it moved south against the Absaroka Range, filling the lower ends of valleys in that range and even overflowing the lower passes in the Clarks Fork-Sunlight divide. This ice and its moraine dammed the Sunlight Valley and formed a lake, the aggradation of which has floored the Sunlight basin. The later glaciation was of the normal valley type with a glacier extending part way down Sunlight Creek Valley. A few small glaciers still exist today.