Overview: The southern Plains are distinguished by short grass prairies . . . hot, dry summers, and cold, windy winters. But in spite of these tough climatic conditions, the area is rich in human history. Indeed, the southern Plains are called the cradle of North American culture Chapter 1: Alibates Flint Quarry National Monument (Texas) Chapter 2: Capulin Volcano National Monument (New Mexico) Chapter 3: Fort Union National Monument (New Mexico)