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dshamilla

Revisiting Spergen Hill, Indiana And Some Of Its Mississippian Micro-Fossils

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dshamilla

This is my first "new topic" post to the FF, so I hope I'm doing this correctly.

If you have a microscope or equivalent and a current or potential interest in micro-fossils, you might enjoy collecting at the following historic locality:

Mississippian Salem Limestone, about 5 miles east of Salem, Indiana off Rt. 160; Spergen (Spurgeon) Hill, railroad cut (Manon RR) paralleling S. Harristown Rd, 0.75 mi north of Rt. 160; south end of Trackside Road; approximately 140 meters S of Harristown, Washington Co., Indiana; diminuitive fauna; Universal Transverse Mercator (UTM) coordinates: 16S 585024.04 4272332.25.

My first introduction to micro-fossils was in a paleontology lab I took during the 70’s with the focus of study on the foraminiferid, Endothyra baileyi (now called Globoendothyra baileyi). These tiny specimens were labeled “Spergen Hill” on their container without further description.

A few years later, I was able to locate the source of the specimens as the type locality for the Salem Limestone (formerly, Spergen or Spergen Hill Limestone) of Middle Mississippian or Meramecean (Valmeyerian) age. Sratigraphically, it sits above the Harrodsburg Limestone and beneath the St. Louis Limestone. The locality is a railroad cut at Spergen Hill, just south of Harristown, Washington County, Indiana. The cut is relatively narrow and much caution is advised upon the advent of trains entering the cut.

The rock at this locality is a medium to coarse grained, tan to gray, crossbedded calcarenite containing mostly microfossils. Macrofossils (somewhat sparse) are present in the formation but nowhere near the quantity of the microfossils (G. baileyi has been estimated at 1,000 / in3 in some portions of the strata). Besides single-celled eukaryotes (e.g., Globoendothyra), representatives of most of the major phyla are present in diminuitive form or as tiny fragments of the macro fauna (spines, plates, columnals, etc.)

I’ve visited the location at least three times in the past and besides collecting macrofossils on these visits, I have also accumulated a quantity of the rock containing the microfossils. On arriving home, I pulverize the collected rock with a sledge to a fine granular size and wash and strain the residue through a porous cloth to remove any extra fine material (rock dust) The washed residue is then dried and placed in labeled plastic bags. Then, in the dead of winter when collecting is not possible for me and the “urge” to collect is compelling, I drag out a bag, place some of the residue in a shallow container under my scope and go fossil collecting and identifying! I use a very fine-pointed forceps, which I periodically ground to a piece of rubber (to avoid static electricity buildup) to pick out fossils from the residue. I find it a bit better for collecting the micros from this locality than using a wetted fine paintbrush. This location has been estimated to contain over 100 species of invertebrates on a micro level. More information can be found at http://www.fallsoftheohio.org/SalemMicrofossils.html.

The attached photos were taken for a program I was giving on Indiana fossils to illustrate single-celled eukaryotes (Protozoa). The first photo shows a random selection of micro-specimens of various phyla collected from the residue with an emphasis on the G. baileyi. The second and third show sorted G. baileyi specimens and G. baileyi specimens with matrix, respectively.

Two free texts with plates are available on some of the Spergen Hill microfauna at the following websites:

Whitfield, R.P. On the fauna of the Lower Carboniferous limestones of Spergen Hill, Ind., with a revision of the descriptions of its fossils hitherto published, and illustrations of the species from the original type series. Bulletin of the AMNH; v. 1, article 5. (free download)

https://books.google.com/books?id=ebYPAAAAIAAJ&pg=PA241&lpg=PA241&dq=whitfield,+R.P.+On+the+fauna+of+the+limestones+of+Spergen+Hill&source=bl&ots=iFhHvpc7qf&sig=XNpUBo45hKPRICv5fLdb0AlJktA&hl=en&sa=X&ei=pO8_Ve70G-vlsATq-4EQ&ved=0CCQQ6AEwAg

Cumings, E.R. et al. Fauna of the Salem Limestone of Indiana. (free download).

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=https%3A%2F%2Fscholarworks.iu.edu%2Fdspace%2Fhandle%2F2022%2F12889&ei=G_o_Va3_CveasQSCu4HADA&usg=AFQjCNGsTNbr2RKBBebd6bnuISOcqvMsPw

post-12742-0-11358300-1430320541_thumb.jpg

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dshamilla

Here are the 2nd and 3rd photos.

post-12742-0-29015500-1430321549_thumb.jpgpost-12742-0-89950600-1430321606_thumb.jpgHere are the 2nd and 3rd photos.

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Diceros

I'm interested in the preservation of the m. Mississippian snails shown here. They aren't steinkerns, the shell is present. Unlike the forams, ostracods, and echinoderm elements, which are originally calcitic; and the brachiopod, which is phosphatic; the snail shells would originally have been aragonitic (which would certainly not have survived in the limestone). Were the snail shells recrystallized to calcite at some point? Some have said the Paleozoic coral have also altered from aragonite to calcite, others that they were calcitic to start with. Any information on this?

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Auspex

If this, your first topic, Is any indication of what we have to look forward to, you have just made a bunch of friends here!

Outstanding, highly informational content: Thank You! :)

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dshamilla

On the preservation aspect, I've always thought of re-crystallization from original aragonite to calcite. To back this thought up you can search your local library for "Developments in Sedimentology 51, Diagenesis IV" or purchase it, if you have about 60 bucks, or google [paleozoic gastropods diagenesis] and open "Diagenesis, IV - Page 219 - Google Books Result" for an informative paragraph on paleozoic gastropod and pelecypod preservation. The google result only gives a preview of the book but most fortunately displays the info in question.

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Packy

Very good post and photos. That rails line has been closed for a couple years to daily traffic, but it is maintained well. It is a very nice location for microfossils.

Packy

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ZiggieCie

This is what I think of your first post. :yay-smiley-1::yay-smiley-1::yay-smiley-1:

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