Welcome to the White Illusion ⚪!
Answer the quesitons below to log this cache!
This EarthCache is located within Arlington Memorial Gardens. At the posted coordinates is a chair-shaped memorial composed entirely from white stone. At first glance, the memorial looks uniform in color and material, but observation reveals an important geological contrast. This memorial is constructed from two very different materials that look deceptively similar: natural white marble and man-made white concrete at the base.
Please remember that this is a memorial site. All observations can be made visually, no touching, climbing, or disturbing the structure is required.
What Are You Looking At?
The memorial is composed of:
- White marble forming the chair itself (seat, arms, sides, and back)
- White concrete forming the stepped base beneath the chair
Although both materials appear white, they have very different origins. Marble is a metamorphic rock that began as limestone. Deep within the Earth, heat and pressure caused its calcite crystals to recrystallize, creating a dense stone that often displays subtle veining, mineral streaks, and a smooth, refined surface. Concrete, by contrast, is a human-made material created by mixing cement, sand, gravel, and water. While it hardens into a stone-like mass, it lacks crystal structure and forms through an entirely artificial process.
What is the Difference?
Comparing these two materials:
- The chair displays faint gray veining and soft, irregular lines, classic indicators of marble. The edges are crisp, and the surface appears relatively smooth and dense.
- The base shows rougher texture, exposed aggregate, small pits, cracks, and surface flaking. These features are typical of weathered concrete, especially where freeze-thaw cycles occur.
In several areas of the base, the white surface coating has worn away, revealing a darker, rougher interior, an important clue that this material is not natural stone.
How to Tell Marble from Concrete
When identifying these materials in the field, consider several sensory and visual cues:
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Texture: Marble feels denser and smoother; concrete often has a sandy or slightly rough feel.
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Luster: Marble may have a subtle shine or polish, while concrete is typically matte.
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Edges and joints: Marble is usually cut into precise blocks with smooth edges. Concrete may show seams or mold lines from being poured into forms.
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Temperature: On a cool day, marble will often feel colder to the touch due to its higher thermal conductivity.
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Color variation: Natural marble often has soft color changes or veins, while concrete has a more consistent appearance (except where weathering or surface coatings are involved).
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Veining: Marble often contains natural veining or swirling patterns created by mineral impurities during its formation. These veins can appear as light or dark lines running irregularly through the stone. Concrete, by contrast, lacks true veining; any color differences tend to be subtle, blotchy, and without directional flow.
LOGGING REQUIREMENTS
Please complete the tasks and questions below, and send me your answers. If logging for a group, please include the names of everyone in your group.
1) Describe one visible texture difference you observe between the marble chair and the concrete base. What feature helped you identify each material?
2) Examine a less-weathered area on both materials. Do you notice a color or texture difference between the “white” concrete and the marble there? Describe what you see.
3) Take a photo of yourself (or personal item) with the memorial. You can attach it to your found it log (required).