What is Weathering
According to Merriam Webster Dictionary, weathering is “the action of the weather conditions in altering the color, texture, composition, or form of exposed objects; specifically : the physical disintegration and chemical decomposition of earth materials at or near the earth's surface.”
There are two basic classifications of weathering processes – physical and chemical weathering; and each can involve biological or non-biological components.
Physical weathering, also called mechanical weathering, is the class of processes that causes the weathering of rocks without chemical change. The primary process in physical weathering is abrasion. Thermal stress weathering occurs when temperature changes cause the expansion and contraction of rock. Frost weathering occurs when water seeps into cracks in the rock, and then expands as the water freezes, exerting pressure on the surrounding rock. Wind can carry sand and other sediments, which over time can wear away the surface of rocks. Plant roots sometimes get into cracks in rocks and pry them apart, resulting in disintegration.
Chemical weathering changes the chemical composition of rocks, often when water interacts with minerals to create various chemical reactions. One of the most common chemical weathering processes is carbonation, where atmospheric carbon dioxide reacts with chemicals in the rock. Carbonation occurs on rocks which contain calcium carbonate, such as limestone and chalk. Acid rain also causes chemical weathering. A number of plants and animals may create chemical weathering through release of acidic compounds. Lichens, algae, and moss all produce various chemical compounds that can react with chemicals in some rocks.
The Properties of Different Rocks and Materials Used for Gravestones
The most common materials used for gravestones in this cemetery include granite, marble, limestone, slate, and sandstone. Granite and marble are not native to the area; these stones were imported from elsewhere. Limestone, slate, and sandstone are quarried locally, although gravestones made from these materials can be from local or imported stone. Additionally for a short period headstones were also made of zinc Granite is an igneous rock which consists mainly of quartz, mica, and feldspar. It is granular in texture, and can be pink to gray in color, depending on their chemistry and mineralogy. Granite is hard and tough, and therefore it has gained widespread use as a construction stone.
Marble is a metamorphic rock composed of recrystallized limestone. Marble is commonly used for sculpture and as a building material. Marble has been used in sculptures, buildings, and gravestones since classical times. This is due to its softness, which makes it easy to carve, its relatively homogenous consistency, and a resistance to shattering.
Slate is a fine-grained, foliated metamorphic rock that comes from an original shale-type sedimentary rock composed of clay or volcanic ash. Slate is foliated, or layered. It commonly is formed in layers that can be split or broken apart. Because of this foliation, slate is commonly used to make roofing tiles. Due to its resistance to heat and its chemical inertness, slate has been used for laboratory bench tops. In areas where it is available, high-quality slate is often used for tombstones.
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite. Many limestones are made from the skeletal fragments of marine organisms such as coral or foraminifera. Like most other sedimentary rocks, most limestone is composed of grains, making it somewhat porous. Limestone was a popular building material in the late 19th and early 20th centuries. The Bloomington, Indiana area has long been a source of high quality quarried limestone, and much of the limestone used in the Cincinnati area came from Bloomington. Limestone and marble react with acid solutions, making acid rain a significant problem to the preservation of gravestones made from them. Limestone was also quarried in an open pit and tunnel mine just north of Lewisburg.
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains. Sandstone is usually very porous, which allows percolation of water and other fluids. Sandstone was commonly used for headstones because it was inexpensive, available locally, and easy to carve. Unfortunately, because of its porous nature, sandstone headstones are especially prone to damage due to weathering.
Zinc is the fourth most widely used metal after iron, aluminum, and copper. Zincs major use is for corrosion protection coatings on steel (galvanized metal); as die castings, as an alloying metal added to countless other metals, as chemical compounds in rubber, ceramics, paints, and agriculture, and in pharmaceuticals & cosmetics. It’s also a necessary element for proper growth and development of humans, animals, and plants. Zinc was also marketed under the name "White Bronze" Monumental Bronze Company, of Bridgeport, Ct; made zinc grave markers and large monuments & statues from 1874 to 1914.
The term "White Bronze" was used only to make the monuments sound more appealing. It wasn't bronze at all. Zinc in its pure form was used. Monumental Bronze Company was the only company to have ever manufactured monuments and grave markers made of zinc. All the casting was done in Bridgeport, although most assembly of the final product was done by the subsidiaries.
Logging this Earthcache
In order to log this Earthcache, examine the following headstones:
The coordinates on the cache page takes you to a large granite double headstone. Rhoda and Daniel Cassel are the names on the stones.
5 Feet to the North there is a waypoint for the marble headstone of Esther Hall.
Pass 3 more marble headstones to the North there is a waypoint for a Sandstone Headstone. You should see the husband of Mary Ann.
Go Northeast to the next waypoint to the Zinc Headstone of the Sloan family. It is also a waymark WMVF1P.
After you have examined the headstones, message or email the answers to the following questions. Reference the type of stone (not the name on it) in your answers. If doing as a group you may have one send the answers for all:
1. Examine the lettering and edges of each stone. Is one easier to read than the other? Which headstone shows the most signs of weathering?
2. Examine the texture of the flat surfaces of each stone. A) Which stone is the smoothest? B) Which stone(s) if any have cracks or other textures that would allow water to seep in?
3. Examine the limestone bases of each headstone. How have the bases weathered differently than the rest of the headstones?
4. Are there signs of biological factors that would cause weathering on any headstone? If so, what are they?
5. Rate the headstones in rank order of 1 being the least weathered to 4 being the most weathered.