This is Throwback Thursday #219. In these, we look back into the past at ESCONI specifically and Earth Science in general. If you have any contributions, (science, pictures, stories, etc ...), please sent them to [email protected]. Thanks!
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On June 17, 1951, ESCONI held a field trip to a quarry in Joliet, IL. As seen in the map below, the quarry was located near Nowell Park in Joliet, which has since been recovered as a lake with part used for construction trucking.
Afterwards, the group went to a large gravel pit... no location was provided. A full report of the trip appeared in the July-August edition of the ESCONI newsletter.
REPORT ON JUNE 17TH FIELD TRIP
The morning of June 17th promised a beautiful day for our second outdoor field trip as 24 cars rallied around our rendezvous at the Joliet High School. With Dr. Fleener leading the group and President Jay and Mr. & Mrs. Longnecker of the Joliet Mineralogists engineering the project, we were off to a fine start.
Leaving the caravan of cars in beautiful Nowell Park, we hiked across the road to the quarry and snapped some fine pictures looking over the ledge into the vast expanse as Dr. Fleener lectured on the various strata of rock exposed to our view. After descending into the quarry we were told the interesting story of a certain Northwestern University Professor who staked his reputation on a theory regarding the presence of the great quantities of quartz in the form of chert nodules and seams at the location where we were standing, through the secondary deposition of silica in the ground waters seeping through the lime stone strata. His theory was eventually found to be as near right or better than any previous or subsequent theory. Our attention was also called to "solution pits", possibly caused by small kettle-like depressions near the receding sea or lake but close enough so the water sloshed over into them occasionally. Thus they would be filled with clay, sea life remains, carboniferous material, or whatever comprised the flotsam of that particular arm of the surrounding water. We finally climbed the bluffs following the lead of that agile young man Dr. Fleener and returned to the park for over-due lunch abetted by glimpses of the bathing beauties in the nearby pool.
The afternoon was spent in a large gravel pit. Dr. Fleener explained how the rubble constituting the gravel deposit was generally material scooped up by the glacier while making the great depression now filled by Lake Michigan. At our morning stop the Niagaran limestone was very close to the surface, and the river from the melting glacier sped through its narrow shallow gap at great speed. All sizes of rock and gravel were hustled through. Then immediately the valley became deep and wide. The water'a speed was checked abruptly and the great load of detritus was deposited helterskelter with little more sorting by the water than by the glacier.
The volume scooped out by the glacier over-extending where Lake Michigan now is might have been of the order of 1000 cubic miles of material. Assuming that trilobites, for example, might comprise a small volumetric percentage (.1%) of a l-foot thick layer covering 100 square miles, what portion of the whole does this make? About 1 part in 50 million! Then what chance has a person to find a trilobite in a small portion of a 1000 cubic mile dump? Very, very small; it approaches zero; it can't be done! So our trips served to fill our collective "beans" with geologic lore rather than our collecting bags with tangible bits from days of yore.
P.S. We found a trilobite in the gravel pit!
Photos from the trip