WWII Memorial Spinning Globe EarthCache

The Tennessee World War II Memorial, located in Nashville’s Bicentennial Capitol Mall State Park, is a poignant tribute to the 5,731 Tennesseans who lost their lives during World War II. Dedicated on November 11, 1997, the memorial was designed by Tuck-Hinton Architects in collaboration with Ross/Fowler Landscape Architects and EMC Structural Engineers, with construction by Hardaway Construction Company.

The Spinning Globe Fountain

At the center of the Tennessee World War II Memorial in Nashville stands a large black granite spinning globe. Beneath this globe, water continually flows over the stone base, creating both a powerful visual symbol and a subtle geologic process. Though granite is highly durable, the interaction between stone and water over time results in visible signs of weathering. This EarthCache focuses on how mineral composition, flowing water, and environmental exposure contribute to discoloration and surface changes on the base of the fountain.

Rock Composition: Granite Base

The stone base supporting the globe is granite, a common and widely used igneous rock in public monuments. Granite forms from slowly cooled magma deep within the Earth’s crust and is composed of:

• Quartz: clear to white, highly resistant to weathering.
• Feldspar: pink, white, or gray; can chemically weather into clay minerals.
• Mica (biotite or muscovite): shiny and flaky; breaks down more easily than quartz.

Granite’s hardness and interlocking crystals make it ideal for structures, but it still weathers when exposed to water, especially in features like fountains where water contact is constant.
 

Weathering Processes at Work

Despite granite’s resistance, the following weathering mechanisms are clearly visible at the memorial:

1. Chemical Weathering (Mineral Breakdown and Staining)

• Water, especially slightly acidic rainwater or treated fountain water, reacts with feldspar, slowly turning it into clay.
• Biotite mica may contain iron, which oxidizes (rusts), leaving brown or orange stains on the lighter granite.
• Water can leach minerals out of the stone, creating discoloration or dark streaks as seen in the image.

2. Physical Weathering (Surface Wear and Texture Changes)

• Continuous water flow can abrade the granite surface slightly, especially where water drips and runs off with force.
• Over time, subtle surface roughness may develop in the path of the water, even if not yet visible.

3. Biological Weathering (Biofilm Growth)

• Moist conditions may support the growth of algae, bacteria, or moss.
• These organisms trap dirt and organic material, creating dark or greenish stains that may deepen discoloration.

What to Look For: Signs of Weathering on the Granite Base

1. Color Differences: Look for areas where the granite is darker or stained compared to drier, untouched stone. Notice if there is a brownish or rusty tint—this may indicate oxidation of iron-bearing minerals.
2. Streaking or Discoloration Patterns: Are there streaks or trails that match where water flows or drips? Check if the discoloration follows the direction of gravity or curves around the basin.
3. Mineral Deposits or Crusts: Look near the base or drain area for white, gray, or off-colored crusty patches—these could be dried mineral deposits from evaporated water.
4. Surface Texture Changes: Run your hand gently along the stone—are some areas smoother, rougher, or pitted? Weathered granite may feel less polished or more textured in wetter zones.
5. Biological Growth: Check for faint green, dark, or slimy patches—these could be algae, moss, or biofilm growing where moisture stays constant.
6. Drip and Splash Zones: Watch where water lands or drips off the globe. Are those areas more stained or weathered? See if there is a clear boundary between frequently wet and mostly dry surfaces.

This cache is placed by permission, and a permit is on file with Bicentennial Capitol Mall State Park