Hobbies And Interests
Little Rocks from Big Rocks
Forces of nature have been creating and moving around gravel since prehistoric times. Glaciers, floods, frost, erosion, snow melt, landslides, wind, rain, rivers and ocean currents crush, crack, tumble and push rock formations until gravity settles the pieces into gravel deposits. Common locations where gravel has accumulated include the bases of mountains and hills, floodplains, stream and river beds, ocean beaches and shorelines.
Activities of Gravel Workings
Gravel workings or works, also called gravel pits and quarries, can be as simple as loading gravel from a natural deposit onto trucks and delivering it. Or, large-scale mining equipment, pulverizing machines, drag line scoops, conveyor belts, screens for sizing, washers, massive loaders and trucks can produce, prepare and deliver specialized varieties of gravel on an industrial scale for major projects. Unlike so many other materials, gravel is simple to transport and store. No humidity, fungus or bugs are going to harm it.
Early Use of Gravel in Concrete
While gravel has been used in early forms of concrete for thousands of years, the Romans made major use of it as their "opus caementicium" to rebuild Rome after the fire of 64 AD. The remarkable dome on Hadrian's Pantheon, the temple to all gods, owes its timelessness to a heavy aggregate base and a lighter upper section of pumice-based concrete.
Modern Uses of Gravel
Gravel expresses its versatility through size, composition and shape. Varieties with uniform color and shape work well in zen gardens, paths and walkways. Smooth, rounded gravels are more comfortable to walk on. Sharp-edged, irregular types lock together better to form railroad beds and road bases.
Gravel solves drainage and mud problems on farms and other well-travelled areas such as park paths and parking lots, and serves as a weed barrier. The same solutions work for the home gardener when using gravel as mulch, as patio flooring, in tree wells and flower beds. Gravel both mitigates mud problems and holds moisture in the ground for thirsty plants.
A layer of gravel in fish ponds helps to prevent fish from stirring up soil and disturbing plants. Inside, no aquarium is complete without colorful gravel to anchor plants. Gravel is useful, top to bottom --- flat rooftops are often lined with gravel also.
Gravel beds in constructed wetlands are being used for large scale filtration to control and purify pollution from industrial and agricultural wastewater, irrigation, run-off and sewage treatment.
Environmental Concerns
Gravel works, before clearing out a deposit of gravel, face certain impacts. Wild fish such as salmon and trout use gravel stream beds to spawn. A stream or river channel can be misdirected after much gravel is removed. Gravel-based habitats off islands and ocean shorelines may be highly populated with marine life that will be eliminated. Avoiding destruction of habitat while gathering gravel and restoration of past sites are increasingly important issues of the industry.