EARTHCACHE REQUIREMENTS
Each cacher must send his/her own answers BEFORE logging a find. Enjoy the journey (learning adventure) as well as the destination (smiley earned). Remember to take only pictures and leave only footprints. To get credit for this Earthcache, complete the following tasks:
1. MESSAGE …. What is high-calcium marble?
2. MESSAGE …. Look closely at the rocks. ... a. Describe what you see. ... b. What evidence of metamorphosis is present?
2. LOG …. Post a picture at or near the coordinates. This picture is your log signature.
OPTIONAL - Please respect the time and effort involved in finding and creating this earthcache by adding A and B to your log.
A. JOURNEY OF THE MIND ... Science explains what we observe. Relate (in your own words) something you found interesting in the reading. This adds to your learning adventure and your log.
B. JOURNEY OF THE HEART ... Art shares our personal experience of what we see. Share something special you found on site, and why it is special to you ... prose / story / poem / picture. This is a memorable addition to your log and will make other hearts smile.
NOTE: Suggested visit to these earthcaches is on Sundays when there is no charge to park and traffic is at a minimum.
BUILDING STONES HARRISBURG CHURCHES
Enjoy your journey observing the large variety of stone types
used in the construction of churches.
GEOLOGY OF UNITED METHODIST CHURCH BUILDING
High calcium marble - Extremely pure
Location - Fifteenth and Derry Streets
Age - Pre-cambrian
RESOURCE - Building Stones of Pennsylvania's Capital Area by Alan R. Geyer EG_005.zip - Pennsylvania Department of Conservation
LIMESTONE
"Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris."
MARBLE
"Marble is a metamorphic rock formed when limestone is exposed to high temperatures and pressures. Marble forms under such conditions because the calcite forming the limestone recrystallises forming a denser rock consisting of roughly equigranular calcite crystals."
CALCITE
"Calcite is a rock-forming mineral with a chemical formula of CaCO3. It is extremely common and found throughout the world in sedimentary, metamorphic and igneous rocks. Some geologists consider it to be a "ubiquitous mineral" - one that is found everywhere. Calcite is the principal constituent of limestone and marble."
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BUILDING STONES - Building stones are selected based on the following:
COLOR
A function of the individual colors of the minerals which make up the rock.
TEXTURE - Geologist Definitions
Fine - crystals too small to see, even with a lens .... Medium - crystals visible, but need a lens to identify them .... Coarse - crystals easily seen with naked eye
TEXTURE - Building Industry Definitions
Determined by the size, arrangement, and bonding of the mineral grains within the rock.
Natural - cut along lines of cleavage revealing natural grain giving an undulating surface .... Honed - smooth finish with a slight sheen .... Polished - shine on stone surface .... Flamed - rough surface with an irregular textured finish .... Sand Blasted - textured surface with a matte gloss .... Sawn - semi-smooth, regular finish .... Bush Hammered - pitted or grooved surface finish
DURABILITY
Based on the texture and porosity of a rock. A durable building stone is one which resists the weathering elements in the atmosphere without suffering decay in some way. The main causes of stone decay are Frost / Salt crystallization / Acid deposition.
ACCESSIBILITY
Relatively easy to quarry.
TYPES OF ROCKS - There are three main categories of rocks based on how they were formed.
SEDIMENTARY
Sedimentary rocks are formed by the deposition of material at the Earth's surface and within bodies of water. IGNEOUS
Igneous rocks are formed through the cooling and solidification of magma or lava. Intrusive igneous rocks cool slowly within Earth's crust giving time for crystals to grow. The deeper within the Earth's crust cooling occurs, the larger the crystal size.
METAMORPHIC
Metamorphic rocks are formed when existing rock types are changed through extreme heat and pressure.