Third Grade
Worksheets
Great Sand Dunes National Park and Preserve
Great Sand Dunes National Park and Preserve is in Colorado. The park protects the tallest dunes in North America. Scientists are not sure how old these sand dunes are. They think they are about 12,000 years old! Along with the dunes, this park protects forests, grasslands, wetlands, and mountains.
The dunes lie between two mountain ranges. They are the Sangre de Cristo and San Juan Mountains. Between the mountain ranges is the San Luis Valley. A shallow lake used to cover most of the San Luis Valley. It was called Lake Alamosa. The lake receded. A large sheet of sand was left behind. The sand was blown in opposite directions by wind. Sometimes the wind comes from the southwest. Other times, it comes from the northeast. This caused the dunes to grow vertically. Two creeks carry sand to the floor of the valley. They are the Medano and Sand Creeks. The creeks disappear into the sand. The sand blows back into the dunefield. The wind and creeks help the dunes to remain about the same size. However, the surface of the dunes is always changing.
