Saturday, July 28, 2012

Rocks as Musical Instruments in Eritrea

I don't normally do guest posts, but since I've been busy traveling, and this gentleman's idea was so interesting, I decided to share this from Berhane Meskel Michael - a geologist from Eritrea, East Africa.  I also encouraged him to start his own blog.


Who would have imagined rocks can entertain us besides supplying us the mineral resources that are the backbone of the modern economy.
I never imagined rocks can be used as musical instruments until I visited my village in Eritrea. In the village, the Medhanie Alem (Holy Savior) Church has a hanging xylophone made of rocks. The rocks the church used for this purpose include Precambrian basement metavolcanic and metasedimentary rocks. The law of physics requires that the rocks be sufficiently long and flat so that they generate their unique sound when struck, in this case in the village struck by an equidimensional rock.

Photo 1. Three long flat slabs of rocks hang on steel wires in the compound of the Medhanie Alem Church. The church is seen in the background.
This local rock bell gets to make its pleasant sound to hear on special occasions like when the Holy Savior Day is observed every October. Its sound closely resembles that of the xylophone.

When struck, waves will be generated that will resonate with frequency. The unique frequencies are governed by the type of mineralogy which in turn controls the type of lithology. Thus, in order to make different sounds, it’s obvious you need to collect different rock types as the Medhanie Alem Church did in Eritrea. So, if you happen to see or hike on dull, massive, structure less rocks, or geologically speaking hornfels and other metamorphic rocks, remember they are capable of more than just storing groundwater, oil, gas, minerals and fossils, they can also entertain us.
MY BIO IN SHORT: My name is Berhane meskel Michael, from Eritrea, east Africa. I’m a geologist just now falling in love with blogging. My geological work experience include working as a geophysicist exploring for groundwater, exploration geologist exploring for gold, copper, zinc and potash from volcanic-hosted massive sulfide prospects to the formidable Danakil Depression. I love to read and write poems, mountaineering, cave spelunking and playing football.
Here is me inside a gypsum cave in the Danakil Depression. It’s amazing I’m inside a hole at 90m below sea level. These caves are a cool shelter from the cruel heat of the day that hovers around 48 degree Celsius in June. 

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