Are the Recently Redefined Dayton Formation (Silurian, Llandovery, Telychian) and Dayton Limestone of Orton, the Celebrated Building Stone of Ohio, the Same Formation, or is a Limestone Below the Dayton Formation at John Bryan State Park the Dayton Limestone? Mark A. Kleffner, School of Earth Sciences, The Ohio State University at Lima Old (left) and New Court Houses at Dayton, built of Dayton Limestone (Plate II in J. A. Bownocker, 1915. Building Stones of Ohio, Geological Survey Of Ohio, Fourth Series, Bulletin 18)

Orton Hall on the campus of The Ohio State University in Columbus, Ohio Arrows point to Dayton Limestone portion of Orton Hall. Brassfield Formation is below and Springfield Formation is above.

From: Orton, 1871: Part III. Report on Geology of Montgomery County

From: Foerste, 1935, Correlations of Silurian Formations in southwestern Ohio, southeastern Indiana, Kentucky, and western Tennessee

From Brett et al., 2012, Revised Telychian-Sheinwoodian (Silurian) stratigraphy of the Laurentian mid-continent: building uniform nomenclature along the Cincinnati Arch, Bulletin of Geosciences 87(4),733-753.

From Brett et al., 2012, Revised Telychian-Sheinwoodian (Silurian) stratigraphy of the Laurentian mid-continent: building uniform nomenclature along the Cincinnati Arch, Bulletin of Geosciences 87(4),733-753.

Cemex Quarry and John Bryan State Park serve as the revised type localities for the Dayton Formation. The unit referred to as Dayton Formation in Greene County clearly matches the description presented by Norris et al. (1950), and is unequivocally the Dayton of southwestern Ohio. Here, we define the Dayton Formation in Greene County, Ohio, as a dense, glauconitic, dolomicrite that is tabular bedded with phosphatic staining and hardground surfaces throughout. The Dayton is underlain by the Brassfield Formation and overlain by the Osgood Formation exclusively. The Dayton Formation, as defined herein, does not extend into the Wenlock. The Dayton Formation sensu stricto contains both Ozarkodina polinclinata polinclinata and Pterospathodus amorphognathoides amorphognathoides, as does the base of the overlying Osgood Formation, indicating that the Dayton Formation is restricted to the middle (?) to upper part of the Telychian below the onset of the early Sheinwoodian δ13Ccarb excursion. From Brett and others, 2012, Revised Telychian-Sheinwoodian (Silurian) stratigraphy of the Laurentian mid-continent: building uniform nomenclature along the Cincinnati Arch, Bulletin of Geosciences 87(4),733-753.

Right: John Bryan Dayton type section of Brett et al Right: John Bryan Dayton type section of Brett et al., 2012 as described in Kleffner et al., 2012. Left and below: Cemex Quarry Dayton type section of Brett et al., 2012.

From Brett et al., 2012, Revised Telychian-Sheinwoodian (Silurian) stratigraphy of the Laurentian mid-continent: building uniform nomenclature along the Cincinnati Arch, Bulletin of Geosciences 87(4),733-753.

From: Kleffner et al., 2012, Stillwater Ridge, West Milton section at which no Dayton is recognized based on revision of Dayton by Brett et al., 2012.

Orton & Peppel, 1906: The limestone resources and lime industry in Ohio.

Osgood Formation Dayton Formation Limestone Limestone “Red” Brassfield Limestone at John Bryan type section for revised Dayton below Dayton and above “Red” Brassfield/Clinton, formerly recognized as part of Brassfield. Limestone at Stillwater Ridge West Milton section below Osgood and above “Red” Brassfield/Clinton, formerly recognized as part of Brassfield or as Lee Creek Formation equivalent.

Conodont elements recovered from that limestone unit at John Bryan representing Ozarkodina aldridgei, a species that is known to range from upper Aeronian to lower Telychian strata; it is not known to range into middle or upper Telychian strata. Limestone at John Bryan type section for revised Dayton below Dayton and above “Red” Brassfield/Clinton, formerly recognized as part of Brassfield.

Limestone Conodont element recovered from that limestone unit at Stillwater Ridge West Milton section representing Ozarkodina polinclinata estonica, known only from lower Telychian strata. Limestone at Stillwater Ridge West Milton section below Osgood and above “Red” Brassfield/Clinton, formerly recognized as part of Brassfield or as Lee Creek Formation equivalent.

Isotope values for “Red” Brassfield and limestone at John Bryan Limestone below revised type Dayton “Red” Brassfield Isotope values for “Red” Brassfield and limestone at John Bryan

“Red” Brassfield Limestone Revised Dayton 13C isotope values and curve for “Red” Brassfield, limestone, and revised Dayton at John Bryan

Osgood Limestone 13C isotope values for “Red” Brassfield, limestone, and Osgood Formation at Stillwater Ridge, West Milton section “Red” Brassfield

Two samples from limestone at John Bryan Sample weathered off from early 1900s railroad trestle in Dayton: Dayton of Orton.

Sample from fence post holder from late 1800s or early 1900s in Dayton Sample from near top of limestone at John Bryan

John Bryan, one of two type sections for revised Dayton Formation John Bryan, one of two type sections for revised Dayton Formation. Upper 1.7 meters of what was previously recognized as Brassfield Formation, is a limestone that compares favorably lithologically with building stones from the Dayton area that most likely are Orton’s Dayton Limestone from quarries in the Dayton area. Conodonts recovered from that limestone indicate a younger age for those strata than is currently recognized for the Brassfield anywhere in Ohio, Kentucky, or Indiana. 13C isotope values for the limestone fluctuate, but do record a gradual decrease from those in the “Red” Brassfield below. It is certainly a possibility that the limestone is Orton’s Dayton Limestone.

Cemex Quarry, one of the two type sections for revised Dayton Formation. Lowermost portion of Dayton Formation did react with dilute hydrochloric acid, so it is not a pure dolostone. Rest of Dayton Formation is a dolostone. Only the dolostone portion of the Dayton yielded diagnostic conodonts. Perhaps the lowermost portion is Orton’s Dayton Limestone.

Stillwater Ridge, West Milton section Stillwater Ridge, West Milton section. The limestone previously recognized as “Red” Brassfield or tentatively identified as Lee Creek Formation has mostly higher 13C isotope values than those of the limestone at John Bryan which could possibly be Orton’s Dayton Limestone. Conodonts could also indicate the same or slightly younger age for the unit than the conodonts recovered from the limestone at John Bryan. Limestone

Summary Hypotheses: Limestone at John Bryan above the “Red” Brassfield is not the Brassfield, and is Orton’s Dayton Limestone. The recently revised Dayton Formation is not the formation recognized by Orton as the Dayton Limestone. Research still required to test hypothesis: Continued collection of building stone from the Dayton area that is the Dayton Limestone as defined by Orton, in order to process for conodonts and 13C isotope values, to compare with the conodonts and isotope values from limestone above the “Red” Brassfield at outcrop sections. Thanks to Michael Sandy for providing samples of Dayton Limestone used as building stone.