Williams County Courthouse 🏛️ EarthCache

The Williams County Courthouse, located in Bryan, Ohio, is a prominent historic building that has served the county for over a century. While the upper portions of the courthouse are constructed of brick and other materials, the base of the building is built from large blocks of sandstone. This stone was intentionally chosen for its strength and durability, especially in areas close to the ground where moisture, freezing, and physical wear are greatest.
This EarthCache invites you to take a closer look at the sandstone blocks surrounding the courthouse.

What Is Sandstone?

Sandstone is a sedimentary rock formed from sand-sized particles that were deposited, compacted, and cemented together over millions of years. These sand grains were originally transported by water, wind, or waves and settled in environments such as rivers, beaches, or shallow seas.
Over time, pressure from overlying sediments and natural mineral cements (such as silica or iron oxides) bound the grains together to form solid rock.

Common Types of Sandstone

1.    Quartz Arenite

• Mostly quartz (>90%)
• Very hard and resistant
• Usually light-colored and well-cemented

2.    Arkose

• Contains >25% feldspar
• Often pinkish or reddish due to feldspar and iron oxide
• Grains may be angular and poorly sorted

3.    Lithic Sandstone (Graywacke)

• Contains many rock fragments and clay matrix
• Darker, more mixed in composition
• Often poorly sorted and muddy-looking

4.    Ferruginous Sandstone

• Rich in iron minerals
• Often reddish or rusty in color
• May show visible iron staining

5.    Calcareous Sandstone

• Cemented with calcium carbonate (calcite)
• Reacts with acid (fizzes)
• Often found near marine environments

Composition

• Grains: Primarily quartz, which is hard and resistant to weathering. You may also find feldspar or rock fragments mixed in.
• Cement: Often made of silica, iron oxide (which gives reddish hues), or calcite. The type and amount of cement affect the rock’s hardness and durability.
• Porosity: Sandstone is generally porous, meaning it has small spaces between grains that can hold water. This is one reason why it weathers more easily than denser rocks like granite.

Texture & Appearance

• Grain Size: Uniformly sand-sized, giving it a gritty, abrasive feel, much like sandpaper.
• Surface Look: Uneven, granular, and rough to the touch. You might see small pits where grains have weathered out.
• Color: Varies from light tan to rusty orange or reddish-brown, depending on mineral content (especially iron).
• Layering: Look closely for bedding planes or cross-bedding, which reflect the direction of sediment deposition by wind or water.

Brittleness

One of the most notable characteristics of the sandstone at this site is its brittleness. Unlike tougher igneous rocks, sandstone:

• Fractures easily when struck or exposed to weathering forces.
• Breaks along natural bedding planes, sometimes forming angular blocks.
• Chips and flakes with minimal pressure, especially when moisture gets into pores and freezes.

This brittleness makes sandstone a poor choice for structural support in architecture, but it also makes it an ideal rock to observe erosion and weathering processes.

Why Use Sandstone at the Base?

Sandstone was commonly used for building foundations and lower walls because:

• It can be cut into large, rectangular blocks (ashlar masonry).
• It resists compression well, making it suitable for supporting heavy structures.
• It weathers in a predictable way, often rounding and roughening rather than cracking suddenly.

You may notice tool marks on some stones, showing how blocks were shaped by stonecutters before being set in place. You may also observe weathering effects, such as surface roughness or slight flaking, especially near ground level where water exposure is greatest.