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TRANSCRIPT
Elijah J. Chandler
Sept. 8th 2016
Professor Jay
Sedimentary Geology
Mad River Beach- Sediment Differentiation
Introduction
So it all started on August 30th, 2016. I arrived at Mad River Beach in Arcata,
California with my Geology classmates and our professor. We had our supplies and
our assignment and we were ready to go. The weather was cool and windy with an
overcast that lingered above with the chance of rain. Despite the sun being in
slumber on a bed of clouds the scenery was still beautiful. The sand dunes covered
in vegetation gave a surreal feel to the beach which otherwise would have seemed
ordinary. Our mission was clear and concise; we were to form small teams and
transect the location, scouring for information high and low until we came to a
reasonable consensus of data with which we could compare with our hypothesiWe
formed a group to make observations about sediment as it varied across a west-east
transect at the Mad River Beachs. Our west-east transect spanned from the beach
eastward into the fore dune. We formed an hypothesis about what might control the
variation in sediment characteristics across the landscape. Our hypothesis was
simple: Thethat the topography will lead to a differentiation in sand grain physical
attributes in directthat correlates with correlation to theirthe location of their
deposition.
Methods
I was grouped with two fellow aspiring sedimentologists by the names of
formed a group with Chris (last name) and ConnorConner (last name). We began by
creating a conversion of meters to centimeters to use as a scale as we traversed the
landscape. We decided that every 1cm on the map would equate to approximately
12.53m in actual distance. We began at our first station (ground zero) and dug our
fingers into the earth below us, clenching the tiny grains of sand in our fists and with
our free hand we utilized the power of our hand lenses to inspect the particles
which laid idle in our palms. With this hand lens we were able to deduce the
physical components such as color and angularity as well as compositional
components such as feldspar and chert. With our notebook nearby we didn’t leave
the magnitude of our findings in the hands of our memories alone, nay, we wrote
down these details for further inspection and contemplation later.
To ensure clear and concise data we decided to use the table methodWe
formed a table in which to enter our sediment descriptions. Dividing our note space
into columns we created a chart with We used six categories that represented
sphericity, roundness, sorting, color, compositional source, and grain size, and
notesrespectively. On the reverse page we drew slope morphology lines to indicate
any changes of slope and slope breaks as we travelled across the sand, as well as flat
areas to generalize over long distances with little change. We then drew a two-
dimensional representation of the area that correlates with our morphology map to
enhance the understanding of one who is ignorant to the area. Lastly we made sure
to notate the distance we traveled between each station and specified how many
stations there were which ultimately came to 11 areas including group zero. This
took patience and understanding, both of which we maintained throughout the
process.
Results
Discussion
After gathering as much data and information as we could within the
timeframe we were allotted, we began to observe said data and analyze it.Here I
present our interpretations of the data we collected on our west-east transect. We
noticed the difference in paces to each station and took into account that some paces
may have been off due to the steepness of a hill or the obstacles that disrupted our
straight path. However, we noticed that once the data and the slope morphology
lines were set they were as a mirror image to our two dimensional depiction of the
area. Notwithstanding some generalization on the map our data appears to be
complete and is able to tell the story of the distance we travelled as well as the
description of the sediment we encountered while transecting the beach.
During and after our transection survey and after we finished we noticed
some interesting details about the sand grains in different locations. Initially we saw
that between around ground zerostations one through station three the grain size
and sorting was fairly consistentdid not change much and we hypothesized that this
was most likely due to the direct wind and water affecting the area causing
weathering and transport. We then saw that once we were overAt stations east of
the first large dune, at stations four and five, the sediment was fine grained and well
sorted. We hypothesize that this is because the sediment that was no longer
bombarded controlled by the elements in processes that dominated at stations to
the weststations four and five was fine grained and well sorted. As we reached the
steep bottom base of a dune at station 7, we were intrigued bynoticed the dark
sediment surface got darker., which we perceived We hypothesized this to be
influenced by due to the surrounding charcoal., but was in actuality However, our
observations show that the surface of the sand was darker due to darker grains of
sand that retained a larger had a more mafic compositional structure. As we
continued and finished our transection of the beach, into the dunes, these principles
held true and our findings and data reflected this accordinglyour observations
continued to support our hypothesis.
Conclusion
It was a quest for knowledge and inquisition and in the end science and
persistence prevailed. We ended just as we started, cold and expectant. After
walking the distance we gained a broader understanding and appreciation for the
earth around us, as well as the process that is needed to interpret it. From the bus to
the beach and back we used clear methods to accumulate data and draw conclusions
using our intuition and reasoning. Our hypothesis had been correct after all. There
was definitely a differentiation of sand grain based on its location on the beach and
its proximity to the water.
Table 1. Sediment Sample Observations. Then describe the table with words.
Figure 1. Map and Map Scale Calculations. Then describe the figure with
words.