Warning, this post may contain an excessive amount of geology.
As almost a continuation of our free day, the past 2 days were spent learning about the regional geology here in the Connemara district of western Ireland where we've been staying and doing our mapping. Showing us around was Dr. Martin Feely, a professor at the National University of Ireland in Galway who led us to some of the most iconic rock outcrops in the area, primarily explaining the history of the Connemara Metamorphic Complex and Galway Granite. Connemara is the best known metamorphic inliers of Ireland, meaning it is an area of older rocks surrounded by younger rocks that has undergone varying amounts of heat and pressure that produced the rocks and various minerals within the rocks that we see today.
Our first stop was Claggan quarry. This outcrop consisted of metasediments (sediments or sedimentary rocks that underwent metamorphism) containing beautiful pinky purple andalusite crystals, muscovite, quartz, tourmaline pegmatite veins, and even some ghostly remnants of cordierite.
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| Claggan quarry |
Following Claggan quarry, we drove to our lunch site, the Lakes Marble Formation at Cur Hill aka fold heaven for geologists. Rather than going into the details of these D3 fold structures, I'll let the pictures do the talking...
The last stop of day 8 was Lough Derryclare where we got to see and sample beautiful outcrops of Connemara Marble, a pretty famous rock used in large dimensional slabs for buildings and smaller pieces for jewelry. Why? The banding and folding are various shades of rich to pale green because of the serpentine-rich (and some diopside and chlorite) nature of the rock. Calcite, dolomite, tremolite, forsterite (garnet), graphite, and quartz are also contained within the marble. Embarassingly enough, I was so absorbed with hammering out my own sample...actually samples, a lot of samples...that I didn't take many pictures of this beautiful rock. However, I will have many samples that I will be bragging about and showing off when I get back into the States...(just a forewarning to my friends, family, and roommates :))
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| Martin Feely!!! Pointing at some deformed folding of the marble |
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| Some weathered tremolite in the Connemara Marble |
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| Connemara Marble |
Day 9 started off with some migmatized metasediments of the Cashel Formation. These formed when metagabbros and granites intruded around 470 million years ago, generating an incredible amount of heat (700-800 degrees Celsius) that essentially resulted in the partial melting of the metasediments they intruded into.
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| Migmatites |
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| Martin Feely explaining the formation of the migmatites |
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| On the drive to the next locality |
Skipping a few outcrop stops...we got to the Costelloe Roadcutting outcrop that exposes the granite of the magma-mingling zone where the grainte had molybdenite, chalcopyrite, and even some purple fluorite all along the joint surfaces and quartz veins!
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| The coppery stuff is chalcopyrite and the blue smudges are molybdenite |
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| Chalcopyrite |
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| Chalcopyrite |
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| A smearing of molybdenite |
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| Fluorite |
Best for last, we all got to visit the Costelloe Murvey Granite quarry in which we were able to fan out and start hammering away in an attempt to gather treasures from the hydrothermal veins that contained anything from quartz, calcite, and spessartine (cherry red Mn-rich garnet), to sulfides like fluorite (both green and purple), galena, chalcopyrite, and pyrite. In other words, we were allotted about 30 minutes of as close to bliss as a geology student could get in the area. At least, that's how I saw it. I managed to walk out with a wide variety of some of the best samples I've ever collected in the field. Again we face the problem of "chase was too busy hammering instead of taking pictures." If you want to see what my samples look like, just google the above sulfides I listed out...they look like those.
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| You know you're a geology student when... |
Next up is a new mapping project along the Irish coast with turquoise water and rocky shores.
As a sidenote...HAPPY BELATED BIRTHDAY MAMAW! Sorry I couldn't come visit you with mom and Cam or actually wish you a happy birthday on your birthday, miss/love you and hope to see you sometime when I get back! :)
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