Geological Exploration of Metro Cleveland (GEM-C)
The Geological Exploration of Metro Cleveland tour is a series of Earthcaches which help to illustrate some geology that is hidden within the urban downtown area of Cleveland. These urban earthcaches help to highlight a wide variety of geological topics that are hidden in plain sight - in fact thousands of people walk by these stones every day without so much as a second thought about their origins!
This tour does not need to be done in any particular order and each earthcache is a standalone lesson. As you wander through the streets of Cleveland take a moment to pause and reflect on the lessons you can learn in just a normal city block!
"Granite: ingrained
with torment of fire and weight
Crystal and sediment linked hot
all change, in thoughts,
As well as things."
-Excerpt from "Riprap" by Gary Snyder
As with all earthcaches there is no container to find here, rather you must read through the description below and answer a few questions in order to log this cache as found. Please ensure that you send your answers to the CO via email or message in a timely fashion.
Peace Arriving from the Flames of War - Larvikite
You are standing in front of the War Memorial Fountain, also known as Peace Arriving from the Flames of War. Initially installed in May of 1964 the fountain serves an eternal monument to Clevelanders who served, died, or were declared missing in service of their country. Surrounding the fountain are bronze plaques which list the names of 5,552 Greater Clevelanders who have fallen during times of war between 1899 and to 2014 when the fountain was last updated.
Today we will be focusing our attention on the four carved sculptures at the base of the large bronze statue in the center of the fountain. These stones are carved from a rock known in the trade as Emerald Pearl Granite which originates in the Larvik area of Norway. This stone is an intrusive igneous rock which means that it was formed as magma deep beneath the earth's crust rose slowly to the surface. This occurred between 298 to 293 MYA as the super continent Pangea was separating.
Larvikite is predominantly comprised of feldspar, but it also can contain olivine, clinopyroxene, amphiobole, biotite, magnetite, and apatite. Feldspar creates a brownish coloration to the stone, while olivine creates a dark green hue, and biotite, amphiobole, and apatite create black colorations. The most striking feature of this rock comes from the specific type of feldspar that it contains, known as labradorite feldspar. This feldspar, through the slow cooling process developed an orientation which causes light reflecting from the stone to create varying colors which shine from the stone when viewed from different angles (note this is best observed in bright sunlight). These colors are often described as iridescent, silvery, or bluish. The photo to the right shows a close up view of the feldspar orientation depicting this iridescent reflection. This stone is exceedingly hard and resists weathering quite well due to the nature of its formation.
Logging Questions
- Other than brown, what other colors do you see in the stone?
- What minerals are causing that coloration?
- Do you see any iridescence?
- What physical property (other than appearance) might have played a factor in the architect's decision to use larvikite in this fountain?
- Take a photo of yourself or a personal item in front of the fountain and include it in your log!
References:
- https://dam.assets.ohio.gov/image/upload/ohiodnr.gov/documents/geology/GB5_Hannibal_1992.pdf
- https://geologyscience.com/gemstone/larvikite/