Resting and Weathering

Welcome!

At first glance, this may look like a simple retaining wall, but the stones here are an open-air geology exhibit. By examining these rocks, you’ll explore how geologists classify rocks, how they weather, and why humans choose certain stones for building.

There is no physical container here. Instead, your “find” is earned by observing, learning, and answering the logging questions below.

Required Logging Tasks

To log this EarthCache, complete the following tasks:

1. Rock Type Identification

   • Based on your observations, do you think these blocks are igneous, sedimentary, or metamorphic? What features support your answer (e.g., layering, crystal structure, roughness, smoothness)?

2. Texture and Weathering

   • Compare two blocks: one smoother, one rougher. How do their textures differ? What does this tell you about how the stone weathers over time?

3. Use in Construction

   • Why do you think this stone was chosen for this wall (consider strength, durability, local availability, or appearance)?

4. Optional Photo

   • Take a picture of yourself or a personal object at the site. Please do not reveal answers in your photo.

Earth Science Lesson

Rocks used in construction are chosen for their strength, durability, and appearance. Geologists classify them into three main groups:

• Sedimentary Rocks form from sediments compacted over time. They may show visible layers or grains. Examples: sandstone, limestone.
• Igneous Rocks form when molten rock (magma or lava) cools and solidifies. They may show interlocking mineral crystals. Examples: granite, basalt.
• Metamorphic Rocks form when existing rocks are transformed by heat and pressure. They may display foliation (layered banding) or a fine-grained, dense texture. Examples: slate, marble.

The wall in front of you contains carefully cut blocks of stone. Some appear smooth and uniform, while others show rough, weathered textures. Observing these differences can help you identify the rock type and consider why builders selected it.
Builders often look for:

• Durability (resistance to frost, salt, and weathering)
• Workability (ability to cut stone into blocks)
• Appearance (color, texture, decorative qualities)

Final Thoughts

Stones in our environment are more than construction material—they’re stories from Earth’s history, shaped by natural processes and human hands. By studying them, you can connect the rocks beneath your feet to the buildings around you.

Thank you for visiting this EarthCache and exploring the geology of building stones!

References

Geological Society of America (GSA) - EarthCache Guidelines