Little Christmas MountainLittle Christmas Mountain is a summit in Brewster County, Texas, United States.DescriptionLittle Christmas Mountain is part of the Christmas Mountains where it is set within Big Bend National Park and the Chihuahuan Desert. The mountain is composed of intrusive rhyolite which formed 33 million years ago during the Oligocene period. Based on the Köppen climate classification, the mountain is located in a hot arid climate zone with hot summers and mild winters. Any scant precipitation runoff from the peak's slopes drains into Rough Run → Terlingua Creek → Rio Grande. Topographic relief is significant as the summit rises above Rough Run in one mile. The mountain's toponym was officially adopted on March 9, 1939, by the United States Board on Geographic Names.