Dune Dam facts for kids

Dune Dam is a long sand dune located at the western end of Chaco Canyon in New Mexico. It's found near where the Chaco Wash and Escavada Washs meet. This natural sand dune acted like a dam, creating a small, shallow lake. This lake was important to the Ancestral Puebloans, an ancient people who lived in the area, especially near their large building called Penasco Blanco.

What is the Dune Dam?

The Dune Dam wasn't built by people; it formed naturally over a long time. Strong winds carried sand from the Chaco River, piling it up until it became a very large dune. When the dune grew big enough, it blocked the flow of the Chaco Wash, which is a stream that usually carries water. This blockage caused water to collect behind the dune, forming a small, shallow lake. This lake was close to one of the Ancestral Puebloans' impressive "great houses" called Penasco Blanco. A "great house" was a very large building, often with many rooms, built by the Ancestral Puebloans.

How the Dam Helped Ancient Farmers

The Dune Dam played a big role in helping the ancient Chacoan people with their farming. By stopping the Chaco Wash from flowing freely, the dam prevented the stream bed from getting deeper. This action helped to raise the water table in the canyon. The water table is like an underground level where the ground is completely filled with water. When the water table is higher, it means there's more water closer to the surface. This extra water was very helpful for the Chacoans, making it easier for them to grow their crops in the dry canyon environment.

The Dam's History

Archaeological findings tell us that the Dune Dam broke open, or was "breached," around the year 900 CE. This means the water found a way through the sand dune. However, the Chacoan people were very clever. Sometime in the early 11th century (the early 1000s), they worked to fix the breach. They filled the gap in the dune with carefully placed stones, a type of building called masonry. They also built a special reservoir next to the dam, which was lined with stones to hold water. This stone-lined reservoir was still visible to people as late as 1920.

A Geologist's Question

Even with all the evidence, some scientists still study the Dune Dam to learn more. A geologist named Stephen A. Hall, who studies rocks and the Earth's history, has questioned some ideas about the dam. He noted that there wasn't a clear lacustrine plain behind the dam. A lacustrine plain is a flat area of land that forms at the bottom of a lake over time, as sediment settles. The absence of this plain led him to think more deeply about how the dam worked and what kind of lake it truly created.

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