This is a 2-stage EC.
GZ is the exit outside of Westlake Station on Pine Street. You want to look at the sidewalk, here. The second stage is WP'd.
NOT A NIGHT CACHE. NO STREET PARKING (I wouldn't count on it...there is a paid lot at GZ).
POTENTIALLY SEASONAL - IF THERE'S SIGNIFICANT SNOW (AND THE SIDEWALK IS COVERED) - YOU WON'T BE ABLE TO COMPLETE THIS EC
Objective: to identify, compare and contrast stones and to learn a bit about the geological history of the region (and the station).
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Geology - Controversy!
Westlake station, along with Pioneer Square station, was at the center of a controversy during its construction due to the use of granite from South Africa, then under a boycott against Apartheid rule. After the granite's origins were discovered, the materials were returned. Metro (the government organisation responsible for construction) also had to return shipments of terra cotta tiles that were delivered warped, in the wrong size, and in the wrong color; the planned terra cotta ceiling for the station was instead replaced with a travertine limestone.
Travertine limestone is a form of terrestrial limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and rusty varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. It is frequently used in Italy and elsewhere as a building material. Similar (but softer and extremely porous) deposits formed from ambient-temperature water are known as tufa. Travertine limestone is a sedimentary rock.
Tufa is a variety of limestone formed when carbonate minerals precipitate out of water in unheated rivers or lakes. Tufa is common in many parts of the world, including Nevada, California and New Mexico in the USA.
Image: difference between travertine and limestone
Image: freshwater limestone
Granite in Washington State
Granite is found mainly in Texas, Massachusetts, Indiana, Wisconsin, and Georgia, as these are the top producers of granite in the U.S., accounting for 64 percent of the country's production. In the Cascades (Washington State), granite is a common rock north of Snoqualmie Pass, but occurs very infrequently south of that point. It does not occm at all, except as glacial bould- ers, in the immediate vicinity of the Puget Sound basin, in the Olympic Mountains, or in the southwestern put of the state.
A quarry in Index, 35 miles northeast of Seattle, supplied the salt-and-pepper granite that was used to rebuild the city after a series of fires. The Index granite, technically a granodiorite, was an important building material in Seattle in the early part of the twentieth century. Granodiorite is a coarse-grained (phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar.
Image: granodiorite
Alkali feldspar granite, some varieties of which are called 'red granite', is a felsic igneous rock and a type of granite rich in the mineral potassium feldspar (K-spar). It is a dense rock with a phaneritic texture. The abundance of K-spar gives the rock a predominant pink to reddish hue; peppered with minor amounts of black minerals. Granitic rocks in general are of interest to geologists, geochemists, etc., because they provide 'crystallized' telltale clues of their environment of formation. Alkali feldspar granite is used as construction material in the form of dimension stones, and polished slabs or tiles for building facades, pavements, and kitchen countertops.
"Red" granite is quarried in the USA among other countries.
Image: alkali feldspar granite
Conglomerates are deposited in high-energy environments, such as fast-moving currents of rivers and streams. Some are lag deposits, in which finer sediments are winnowed away, concentrating the heavier gravel-sized particles. Conglomerates make up only a small percentage of all clastic sedimentary rocks.
Image: conglomerate
Diabase, also called dolerite or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase is the preferred name in North America, while dolerite is the preferred name in the rest of the English-speaking world, where sometimes the name diabase refers to altered dolerites and basalts. Some geologists prefer to avoid confusion by using the name microgabbro. In the US, diabase is quarried in the New Jersey Palisades, and the Death Valley region (California).
Image: diabase (polished)
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Responses to submit - if submitting responses for a partner, be sure to include their geocaching name with your response. EACH PERSON, however, must submit their own unique photo demonstrating they were on site (see Q1 below).
I will read and respond to all submissions. To claim a find, logging requirements must be met. If you will be delayed, post a write note until you are ready to send your responses. If there is a concern, I will note that in my response.
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1. Required photo for all cachers - take a photo of you/ your GPS / your caching name near GZ with the street sign of 4th & Pine visible in the photo. Post this with your log.
2. At GZ, take note of the stone inlay on the sidewalk just outside of the Westlake station exit. Describe and identify each of the 4 stones (by name). You will want to refer to the lesson + your observations. For example, the bright green stone with black veins is serpentine. (This is not an answer, just an example of the type of expected response).
3. At WP1, look at the steps leading to the entrance. Describe and identify the stone.
a) ASIDE FROM COLOUR, what noticeable (geological) differences do you see here compared to the stones at GZ?
4. Based on your observations, what can you conclude about the type of stone found at GZ compared to WP1? Recall, there are three types of stone: sedimentary, metamorphic and igneous. What do you see at both GZ and WP1?
5. Optional: enter Westlake station and explore the Mezzanine area (note: if you go beyond and enter the paid zone area, please be sure to have a valid ticket). There are wonderful examples of terra cotta and other granites.
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Thanks for visiting and I look forward to reading your responses.
For those that are new to doing Earth caches, please note that to claim a find you do actually have to answer the questions and submit all components. Read the lesson, look at the features and try your best! 