The EarthCache name is a reference to the poem "In God's Garden" on top of the sundial by Dorothy Frances Gurney, which she wrote in 1882.
As this EarthCache is located in a cemetery, please only come during daylight hours.
Composition & Colors: Granite is one of the hardest types of rock and is crystaline in nature. It is made up mostly of quartz and feldspar which are the lighter colors, the whites and the pinks, that you see when you look at a piece of granite. But, it does comes in a wide variety of colors--greens, whites, browns, yellows, blues, blacks, reds, grays, and more. The minerals prevalent in the specific area of the world and the depth it is mined from determine this variety of color. The relative proportion of the different colored minerals in a granite is largely due to the original source of molten rock that cooled to form the granite. Thus classic granite has a "salt-and-pepper" look. The most common accessory minerals are the black mica biotite and sometimes black amphibole hornblende.
So if the molten rock was abundant in potassium feldspar, the granite is more likely to take on a pink color, and if the molten rock was abundant in quartz and minerals that make up amphibole you will likely get a black and white speckled granite.
Texture & Crystal size: Granite is an intrusive igneous rock that begins as a molten liquid state that solidifies as it cools. The texture is now determined by the rate at which it cooled. The large mineral crystals in granite are evidence that it cooled slowly from molten rock. That slow cooling occurred beneath the earth's surface and required a long period of time. Granite which cools closer to the earth's surface as when it is exposed to air or water, cools more rapidly and the result is a granite with crystals that are smaller. The image below shows the different size crystals and these will vary in each piece of granite depending on how it was formed.Â
Mining Granite: Granite is found close to the surface, meaning it can be cut from shallow quarries. Small holes are drilled to get the shape of the desired block size (making it easier to transport). Explosives are placed into these holes to carefully create a blast that’s just strong enough to separate the granite from the bedrock, without breaking the block itself.
TYPES OF WEATHERING: There are two distinct types of weathering which alter and degrade rocks in different ways:
Physical Weathering​ breaks down a rock's physical structure. For example, in cold environments water that gets into holes in rock and freezes will cause those holes to expand and eventually crack and split the rock. The same process may be caused by salt buildup or growing tree roots. Another form of physical weathering occurs when wind or water causes rocks to rub against each other, smoothing their surfaces. One of the most common types of physical weathering is wedging. Wedging occurs when a substance finds its way into cracks or holes in a rock and expands outward. This widens these cracks and holes, and can cause rock to split apart; this may also occur to exposed brick. Freezing water, crystalizing salt, and growing plant roots are common causes of wedging.
​Chemical Weathering​ changes the chemical structure of rock, causing it to become softer or more brittle. For example, iron in a rock might react with oxygen to form easily degradable rust, or acids in rainwater may remove calcium from limestone and marble. Chemical weathering often precedes physical weathering, making rocks more vulnerable to forces like wind and rain. Chemical weathering​ does not cause physical damage to rock but rather is a reaction between the chemical composition of the rock and outside chemicals. Chemical weathering can make a rock more vulnerable to physical weathering forces. For instance, ​oxidation​ is a process by which oxygen in the air reacts to chemicals in the rock. Iron in rocks can react with oxygen to form iron oxide, or rust. Rust is weaker than iron and makes the rock more likely to degrade. ​Hydration​ is a reaction in which molecules of water are incorporated into the structure of a rock. For instance, hydration causes the mineral anhydrate to convert into gypsum, a less dense mineral that is more vulnerable to outside physical weathering forces.
Logging requirements:
Send a geocaching message or email  with the answers to the questions below. Do NOT post any answers in your online log.
Pick out one piece of granite that makes up the sundial...then answer your questions based on that piece:
1. Based on the cache page information and your observations, does the crystal size indicate that this piece cooled slowly or more rapidly?
2. What is your best estimate to the size of the crystals on this piece? (example: crystals the size of a pea, fingertip, pencil point, etc.)
3. Based on the mineral color chart above and your observations, what minerals do you think make up this piece of granite?
4. Do you see any signs of weathering in the piece of granite you chose? If so, describe in detail. If not, why do you think that is?
5. Post a photo of yourself with only the top of the sundial (don't post photos of the base with the granite pieces please).
*Bonus Question - based on the oxidation you see, what do you believe the metal part of the sundial is made out of?
