Wow. What a day. Today started for me with a healthy breakfast of rice krispers and toast with peanut butter and honey. But not just normal honey, really good honey. I brushed my teeth after the meal and was then ready for an exciting day in the field!
Our first stop was back at the beautiful Cape Foulwind, where we trekked to a lighthouse that overlooked the beach where we’d spent the previous day. After learning that this was, in fact, not supposed to be our first stop we walked back to the van and to another point along the coast. This was also not the area we were looking for, but luckily the rocks proved satisfactory for our purposes. Our subject was a massive massive grey outcrop, and our object was to find out just what this big boy was made of. After a quick seminar in mineral properties based on light, mechanics, and shape we were able to determine that the outcrop was of igneous origin based on the interlocking nature of its grains and that it was composed of feldspar megacrysts (crystals relatively much larger than the rest existing within the composition), quartz, and biotite mica. These mineral presences and abundances told us that the rock was a granite, and with this victory in hand we moved on to our next stop of the day.
After driving south along the west coast we stopped at a sandy beach, our hearts filled with joy at the thought of getting up close and personal with some more rocks in the sunny weather. Little did we know how up close and personal our experience would turn out to be... . After walking a short ways down the beach we stopped at a rock whose composition of feldspar megacrysts, quartz, and bioties was very similar to that of the first outcrop, but this time we couldn’t just take it for granite that it was the same type of rock (haha). Instead, it’s inclined planar fabric and deformed, cracked megacrysts indicated that this rock had experienced shear as high temperatures and oblique pressures caused foliations to form. The high temperatures and pressures necessary to induce this sweating pointed to the fact that this rock had undergone metamorphic processes, what was once an igneous granite was now a meta-granite, more accurately called a gneiss. We patted ourselves on our back for such a gneiss job at rock identification and proceeded northward along the beach, expecting our next subject to be just up ahead.
We soon learned that this was not the case, and as we clambered over boulder after boulder we gained a true appreciation for the angularity of the large clasts. It was pretty hardcore. Our efforts were rewarded (?) after we reached a hidden beach and got to eat lunch, for me an inspired concoction of salami and bread. We couldn’t dawdle over our food, though, as the rising tide and impending rain clouds spelled doom for our upcoming return passage. We quickly marveled at a rock that took metamorphic deformation to a whole new level, the mylonite level. We also saw evidence of extreme deformation within intrusive feldspar deposits in the rock, and there were some super sick curvy bands that made us say “wow!”
Our first stop was back at the beautiful Cape Foulwind, where we trekked to a lighthouse that overlooked the beach where we’d spent the previous day. After learning that this was, in fact, not supposed to be our first stop we walked back to the van and to another point along the coast. This was also not the area we were looking for, but luckily the rocks proved satisfactory for our purposes. Our subject was a massive massive grey outcrop, and our object was to find out just what this big boy was made of. After a quick seminar in mineral properties based on light, mechanics, and shape we were able to determine that the outcrop was of igneous origin based on the interlocking nature of its grains and that it was composed of feldspar megacrysts (crystals relatively much larger than the rest existing within the composition), quartz, and biotite mica. These mineral presences and abundances told us that the rock was a granite, and with this victory in hand we moved on to our next stop of the day.
After driving south along the west coast we stopped at a sandy beach, our hearts filled with joy at the thought of getting up close and personal with some more rocks in the sunny weather. Little did we know how up close and personal our experience would turn out to be... . After walking a short ways down the beach we stopped at a rock whose composition of feldspar megacrysts, quartz, and bioties was very similar to that of the first outcrop, but this time we couldn’t just take it for granite that it was the same type of rock (haha). Instead, it’s inclined planar fabric and deformed, cracked megacrysts indicated that this rock had experienced shear as high temperatures and oblique pressures caused foliations to form. The high temperatures and pressures necessary to induce this sweating pointed to the fact that this rock had undergone metamorphic processes, what was once an igneous granite was now a meta-granite, more accurately called a gneiss. We patted ourselves on our back for such a gneiss job at rock identification and proceeded northward along the beach, expecting our next subject to be just up ahead.
We soon learned that this was not the case, and as we clambered over boulder after boulder we gained a true appreciation for the angularity of the large clasts. It was pretty hardcore. Our efforts were rewarded (?) after we reached a hidden beach and got to eat lunch, for me an inspired concoction of salami and bread. We couldn’t dawdle over our food, though, as the rising tide and impending rain clouds spelled doom for our upcoming return passage. We quickly marveled at a rock that took metamorphic deformation to a whole new level, the mylonite level. We also saw evidence of extreme deformation within intrusive feldspar deposits in the rock, and there were some super sick curvy bands that made us say “wow!”
Our wows were replaced with woes as we began our return journey, because the world had decided that climbing over rocks was not difficult enough and increased the challenge with a light rain. Despite our fears (or in Conrad’s case, excitement) we made the traverse with ease and were left with a sense of accomplishment at our physical prowess. Finally we stopped at our last rock of the day, a mysterious feldspar and quartz powerhouse surrounded by a gneiss outcrop. We learned that the concoction was a pegmatite and concluded that it was an intrusive deposit that had cut the gneiss after the gneiss had been deformed. Gneiss! The presence of both biotite and muscovite mica bands within the pegmatite also revealed to us that the deposit was rich in aluminum, indicating that it originated from a crustal source, as opposed to the gneiss, which most likely originated from magmas coming from the mantle.
Our discoveries complete, we returned to the Westport field station and enjoyed a delicious meal of lamb chops, rice, and veggies cooked by Guil and Lydia. Our last day in Westport left us sure that it was the bestport in town and we slept like rocks after our big adventure.
John
Our discoveries complete, we returned to the Westport field station and enjoyed a delicious meal of lamb chops, rice, and veggies cooked by Guil and Lydia. Our last day in Westport left us sure that it was the bestport in town and we slept like rocks after our big adventure.
John
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