An EarthCache is unlike most geocaching; there isn't a physical container to locate! You will instead see something geologically interesting and be introduced to the underlying science. To count your visit as "found", questions at each site will need to be answered. Please e-mail (or message) your responses to Unitzoid. Any posted logs without answers sent will be deleted.
Site #1: McCleary
N 38° 57.024 W 092° 20.193
For three generations, the McCleary family worked in the legal system. Glenn Avaan McCleary, the eldest, served as the University of Missouri's Dean of the School of Law from 1939 to 1958. While his son, John, and grandson, Randolph, followed his example, they also sought a more creative endeavor: music! Both were avid musicians, and it's notable that natural musical staff lines grace the top of the family monument.
Wait, musical staff lines? Not quite! What you are seeing is how a sedimentary rock is created. This is one of three kinds of rock we'll touch on while visiting different sites around the cemetery.
Sedimentary rock is formed by the layering of sediment (mineral and rock grains) cemented under pressure from upper layers over time. Bedding, or differing layers, are shown by color or composition contrasts (hence the appearance of staff lines). These rocks also sparkle! Shine a bright flashlight at the surface, and you will see light bouncing around inside small, mineral crystals. Around them you can make out individual sediment grains.
More obvious than the grains are cracks that have formed on the bottom half of the northern side. Fissures such as these open the door for mechanical weathering (which, sadly, doesn't involve robots). Mechanical weathering is when a rock breaks down due to forces that don't change its chemical makeup. Missouri's climate allows ice to form and expand in the cracks during winter which melts away the following spring. This slowly pushes the rock apart in a process called frost wedging.
Question 1) Do the cracks in the rock run in the same direction as the bedding layers?
Question 2) Is there evidence of previous mechanical weathering on the surface? You are looking for exposures of rock that are rougher in texture or not as smooth as the rest.
Site #2: William O'Rear/O'Reer
N 38° 56.941 W 092° 20.218
William O'Rear (or O'Reer) settled in Boone County after 1823 following a lengthy series of occupations. He carries the distinction of serving the Virginia Militia during the Revolutionary War and possibly being the first slave trader west of the Allegheny Mountains. What makes his burial site geologically intriguing? William has two monuments, and one can be made from the other!
Take a look at the original, more faded monument with three points. It's composed of sedimentary limestone with many fossils. Limestone, when subjected to heat and pressure underneath the Earth over time, transforms into marble! When one rock turns into another, the resulting rock is called metamorphic.
You can tell a metamorphic rock by its compact texture with stretched or compressed features such as crystals, fossil imprints, or distorted layers. Look at the top of the newer, brighter monument. See how the crystals from the original limestone have grown and were squeezed tightly together into a jumble? That's heat and pressure at work! The resulting stone is less porous and stronger than the original.
Alas, marble eventually succumbs to weathering. Walk twelve and a half feet to the southwest from William's grave markers. There, you will spot a tall, marble obelisk with a very faded torch, rose and shield facing the road. What you see is the effect of chemical weathering where a rock is broken down by reactions with liquids or gasses. Rainwater reacts with the calcium carbonate (CaCO3) crystals in marble dissolving them away. Limestone has the same weakness and dissolves quicker due to being more porous.
Question 3) Each monument for William has a different spelling of his last name (O'Rear and O'Reer). Which one is limestone and which is marble?
Question 4) Other than faded features, how would you describe the weathering of what once was the smooth surfaced marble obelisk? How is it different from William's marble marker?
Site #3: George C. Swallow
N 38° 56.930 W 092° 20.261
The big, granite boulder is a dead giveaway of who's buried here: George C. Swallow, first state geologist of Missouri! It was one of several titles he held, and all were controversial in their own right. Such a heavy rock is fitting for a man steadfast in his actions . . . and our ongoing geology lesson.
Granite is an igneous rock. Igneous rocks are made from hot, molten magma (liquid rock) that has cooled and solidified. Identifying them can be tricky; how long they take to cool determines what they look like. Those that cool rapidly are smooth with crystals and grains all but invisible to the naked eye! Longer cooling periods (usually under the surface of the Earth) create a grainy appearance and larger crystals.
Swallow's monument is a good example of differing cooling periods. At the right side of the bronze plaque you will see a vein of rock that's a lighter color than the rest. You can trace it across the top and around the entire boulder. Shining a bright flashlight on the vein and surrounding rock will reveal which has larger mineral crystals.
Question 5) Which cooled slower, the vein described above or the surrounding granite?
Site #4: B. E. Smith
N 38° 56.892 W 092° 20.284
First things first: Do not touch B. E. Smith's monument! This particular marker is small and can be found between Elsie Opal Sexton (1910 - 1949) and Rosa Smith (1886 - 1967).
You may be asking, "What's up with the warning?" As you saw, the granite at Swallow's grave is quite solid and can handle most anything thrown at it (much like the man). The granite here, in contrast, is soft and known as saprolite. Saprolite is a rock that has succumbed to the effects of chemical weathering.
Granite, especially from Missouri, is mostly made of silicon crystals known as feldspar. Feldspar decomposes into clay when weathered by water. Looking at the top of the B. E. Smith marker, you can see what happens when feldspar is removed. Rounded bits of granite remain that will continue weathering down to small grains of rock. Given time, these grains may become part of a new local sedimentary rock.
(insert Circle of Life music here)
Question 6) Based on what you see, what kinds of weathering are present on B. E. Smith's marker: mechanical, chemical or both? Why?
Site #5: Geocacher's Choice (Optional)
Okay, time for some extra credit that is completely optional! There are many, many awesome monuments throughout Columbia Cemetery. Explore a bit and find one that speaks to you! By now, you should be able to tell what kind of rock it is (sedimentary, metamorphic or igneous) and how it weathered. Take a photo and provide GPS coordinates if you can.
Question A) Who is buried at your chosen monument?
Question B) Is your monument sedimentary, metamorphic or igneous?
Question C) Do you see evidence of weathering on your monument? Which kind?
Sources
Baedecker, Philip A., and Michael Reddy. "The Erosion of Carbonate Stone by Acid Rain: Laboratory and Field Investigations." Journal of Chemical Education Volume 70.2 (1993): pp. 104 - 108.
Codd Genealogy. Col. William O'REAR. http://freepages.genealogy.rootsweb.ancestry.com/~coddingtons/12631.htm
Douglass, John. Chemical Weathering. http://www2.pvc.maricopa.edu/~douglass/v_trips/wxing/introduction_files/chem-wx.html
Mertens, Randy. Border Ruffian Savant. https://cafnr.missouri.edu/2012/11/border-ruffian-savant/
Missouri Department of Natural Resources. A Collection of Missouri Rocks and Minerals. https://dnr.mo.gov/geology/docs/rocksetbooklet.pdf
Missouri Department of Natural Resources. Granite. https://dnr.mo.gov/geology/geosrv/geores/indmin/granite.htm
Missouri Law Review. "Glenn Avann McCleary." Missouri Law Review Volume 31 (1966): pp. 1 - 3.
Montgomery, Carla W. Physical Geology. Dubuque : Wm. C. Brown Publishers. 1987. pp. 27 - 42, 46 - 61, 66 - 76, 88 - 97, 360 - 364.
Randolph Lawrence McCleary Obituary. "Randolph Lawrence McCleary - April 11, 1966 - Nov. 19, 2015." Columbia Missourian 23 Nov. 2015: http://www.columbiamissourian.com/obituaries/family_obituary/randolph-lawrence-mccleary-april-nov/article_78629c68-925b-11e5-8f1a-bf92e04e304e.html
Rootsweb. John Rigby McCleary. http://worldconnect.rootsweb.ancestry.com/cgi-bin/igm.cgi?op=GET&db=vedemarce&id=I110159
Permission to place this EarthCache was generously provided by Tanja Patton, Superintendent of Columbia Cemetery. She shares my thanks with Ted Craig for his insights on the cemetery's geology.