Soldier and Salina Canyon Dam

The dam was built during the early 1930s to trap silt from floods that were rushing down Salina and Soldier Canyons. In that task, the dam was successful — slowing water flow and allowing sediment to settle. Over time, this encouraged the growth of woody riparian vegetation downstream, while the surrounding pinyon-juniper hillsides remained largely unchanged. The choice of stone was practical: builders quarried local limestone, which was abundant, durable, and easy to shape. This connection to the local geology not only made construction possible with available resources but also left behind a structure that still reflects both the geological history of the region and the human response to environmental challenges nearly a century ago.

🌍 Earth Science Lesson

This site is the remains of an old dam built with local stone. The builders primarily used limestone, a sedimentary rock formed when the shells and skeletons of marine organisms compacted and cemented on ancient seafloors. The light gray to tan blocks with their fine texture and blocky fractures are typical of limestone.

To hold the dam together, a mortar/aggregate mix was used. This mix includes a variety of smaller local rock fragments, such as quartz, sandstone, or chert. By comparing the dam’s cut limestone blocks to the aggregate, you can see two distinct parts of the region’s geology in one structure.

Over the decades, the dam has also been shaped by weathering. Limestone is especially vulnerable to weathering because it reacts with slightly acidic rainwater and also breaks down physically along fractures. As a result, cracks, crumbling surfaces, and exposed aggregate can be seen throughout the structure.

Together, these features make the dam a unique example of how humans used local geology to build — and how natural processes continue to change it.

Why Limestone Matters

• Geological Record: Holds fossils and clues about Earth’s past environments.

• Human Use: A common construction material for dams, buildings, and cement.

• Landscape Shaping: In nature, limestone weathers into cliffs, caves, and sinkholes.

This old dam highlights how early builders took advantage of the geology at hand to create lasting structures. Even though it has weathered over time, the rock itself continues to tell the story of its ancient origins.

📍 The Site

At this location, you are standing on what was once a working dam. Notice how the dam was engineered with cut limestone blocks on the main faces, while rubble and aggregate mortar were used to reinforce the structure. Decades of weathering have exposed the textures and breakdown of the rock, providing a great opportunity to study limestone in both natural and human contexts.

📝 Logging Tasks

To log this EarthCache, please send answers to the following questions to the cache owner (do not post them in your log):

1. Stone Identification
   Describe two visible characteristics of the dam’s main blocks that indicate they are limestone (for example: color, fine texture, blocky fractures, or fossil/shell evidence).

2. Aggregate Analysis
   Look closely at the mortar/aggregate areas. How do the small fragments differ from the cut limestone blocks? Name one type of rock or texture you notice.

3. Weathering Evidence
   Find one example of weathering on the dam (such as cracks, crumbling stone, or exposed aggregate). Describe what you see happening to the rock.

4. Bonus (Optional Photo Task)
   Take a photo of yourself or a personal item with the dam visible in the background. Please avoid showing your answers in the picture.

⚠️ Important Notes

• This is a historic site. Please do not climb on the dam or remove rocks.

• Be cautious of uneven surfaces and edges.

• Respect the natural environment and practice Leave No Trace.

✅ Logging Requirement Reminder: To claim a “Found It,” you must send your answers to the cache owner.