The scene opens on the Westport Field Station, with sheets of rain bombarding the sturdy cabin. A glimmer of hope, the clouds part, and reveal the beautiful day before us.
After a 20 minute drive, we arrived at the appropriately named Cape Foulwind. Before us was a beautiful, but very windy, beach with impressive cliff faces lining its coast, Guil and Lydia gave us our task for the day, which was to create a graph depicting the age and composition of the sediments present at the outcrop —or, a stratigraphic column. With minimal guidance and our reins newly loosened, we set out to do so. Using what we had learned from the last few days, we ran loose into the field to characterize the rock faces that were before us. Aside from our initial tasks of piecing together the puzzle of what the heck formed the slanted rocks in front of us, we were told to watch out for seals that were known to pop up on the beach!
In terms of characterizing the rocky outcrops, we needed to determine which sediments came first in order to conceptualize the column that we ultimately had to build. Luckily for us, there were two prominent crossbeds, which are wave-like packets of sediments transported by wind or water. We observed that the upper layers were indeed younger than the lower layers, as the crossbeds were truncated at the top.
Next, we set out to determine how many main rock units were present at the site. The first unit we saw was a silty grey arch formation that had distinctive layers and some shells that were interspersed throughout the formation. Interestingly enough, there was also a soil horizon at the top of this unit that we identified thanks to its dark color and oily feel, indicating a significant time gap between the silty layer and the next deposit. Speaking of which, the next unit was an orange sandstone that sported the very same crossbeds that helped us determine the “up” direction.
Further along the beach, we spotted a bumpy, creamy rock unit that consisted of fossilized shells and little to no other sediments. We classified this to be a fossiliferous limestone which was younger than the sandy orange unit we had seen previously. Above this unit, we saw a massive version of the first unit, except with fewer shells and well-preserved corals than must have been millions of years old! This young formation was an impressive 15 meters tall (at least!) and stretched along the remainder of the beach. It seemed as though we were looking back in time!
From these observations, we determined a sequence of events in which sea levels dropped from a deeper marine environment, as shown by the first layer, to a higher energy river environment that would deposit crossbedded sandy layers. Next, there was a sea level rise to a shallow marine coral reef system that would explain the broken shells we saw in the creamy layer. Finally, we concluded a continuing sea level rise to a deeper marine environment, accounting for the intact fossils preserved within the youngest grey silty layer.
Solving this mystery took a whole lot of time and energy, and called for a rest on the beach! Watching the foam crash against the rocks and the sun set lazily in the distance, our eyes wandered to a darling seal meandering its way along the shore and eventually finding its way back home into the tumbling, frigid sea. Five days into this extraordinary experience, we already knew we loved New Zealand, but this precious sight really Sealed the deal! With such amazing sights both geological and otherwise, we can’t wait to see what tomorrow will bring.
xoxo Conrad & Emma
In terms of characterizing the rocky outcrops, we needed to determine which sediments came first in order to conceptualize the column that we ultimately had to build. Luckily for us, there were two prominent crossbeds, which are wave-like packets of sediments transported by wind or water. We observed that the upper layers were indeed younger than the lower layers, as the crossbeds were truncated at the top.
Next, we set out to determine how many main rock units were present at the site. The first unit we saw was a silty grey arch formation that had distinctive layers and some shells that were interspersed throughout the formation. Interestingly enough, there was also a soil horizon at the top of this unit that we identified thanks to its dark color and oily feel, indicating a significant time gap between the silty layer and the next deposit. Speaking of which, the next unit was an orange sandstone that sported the very same crossbeds that helped us determine the “up” direction.
Further along the beach, we spotted a bumpy, creamy rock unit that consisted of fossilized shells and little to no other sediments. We classified this to be a fossiliferous limestone which was younger than the sandy orange unit we had seen previously. Above this unit, we saw a massive version of the first unit, except with fewer shells and well-preserved corals than must have been millions of years old! This young formation was an impressive 15 meters tall (at least!) and stretched along the remainder of the beach. It seemed as though we were looking back in time!
From these observations, we determined a sequence of events in which sea levels dropped from a deeper marine environment, as shown by the first layer, to a higher energy river environment that would deposit crossbedded sandy layers. Next, there was a sea level rise to a shallow marine coral reef system that would explain the broken shells we saw in the creamy layer. Finally, we concluded a continuing sea level rise to a deeper marine environment, accounting for the intact fossils preserved within the youngest grey silty layer.
Solving this mystery took a whole lot of time and energy, and called for a rest on the beach! Watching the foam crash against the rocks and the sun set lazily in the distance, our eyes wandered to a darling seal meandering its way along the shore and eventually finding its way back home into the tumbling, frigid sea. Five days into this extraordinary experience, we already knew we loved New Zealand, but this precious sight really Sealed the deal! With such amazing sights both geological and otherwise, we can’t wait to see what tomorrow will bring.
xoxo Conrad & Emma
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