Late Academic Period


View of "the flats" above Sherman Falls.

Photograph by: Carlton E. Brett


Late Academic Period (1970's to Present)

Research at Trenton Falls saw a dramatic drop in the number of publications on that locality in the first half of the 20th century. This was in part due to the fact that some of the nation's greatest geologists had established their reputations studying and publishing on these rocks in the 1800's. Consequently geologists, having felt the Trenton was already understood, went elsewhere for their work. Because the geology of Trenton Falls and the Mohawk Valley was considered to be a classical region for field studies, many geology professors used it for educating their students. Perhaps the most famous example of this is the late Dr. G. Marshall Kay. During the course of his 40-plus year academic career, Marshall Kay had introduced many students to the region and several of these began their geological careers investigating some of the problems of the Trenton Group in the type region. The Late Academic Period saw the development of new research programs by students of Marshall Kay's as well as researchers at nearby colleges and universities.

In addition to the development of new research agendas on the Trenton Group and related strata, the New York State Museum saw the need for changing its strategy with respect to service to the geological community and the public. During the early half of the century, much of the focus of the survey staff was dedicated to quadrangle mapping, and to general stratigraphic and paleontologic studies. With the onset of the second half of the 20th century, the goal of the State Paleontologist, D. W. Fisher, was to summarize and produce detailed correlation charts for each of the lower Paleozoic systems preserved in New York State. Detailed charts were compiled by D. Fisher and L. Rickard on the Cambrian, Ordovician, Silurian and Devonian strata of New York State by the 1970's. The intention was to "summarize [the] status of knowledge on these rocks.... [in order to address the needs of' researchers in Early Paleozoic paleoecology, stratigraphic paleontology, stratigraphy, and sedimentology, and to teachers and students of these subjects" (Fisher, 1977; p. 2). Fisher's goal was to "stimulate professional and student alike to test the chronologic and paleoecologic information presented [in these publications]" (Fisher, 1977; p. 2).

If a student or geologist believes that the Trenton or any other New York formation has "been done", then they are very wrong. Fisher challenged us to continue this admirable work when he stated "I urge that additional paleobiologic and stratigraphic research be undertaken in order to fill existing deficiencies in our knowledge of New York 's ... strata" (Fisher, 1977; p. 2).

The following sections present a synopsis of research on Trenton Valls and its vicinity performed by major contributors and their students within the last 30 years. These individuals have published significant contributions to the "problems of the Trenton", with the goal of elucidating new techniques and new ways to look at old problems. With the detailed high-resolution paleobiologic and stratigraphic studies of the last 30 years, great progress has been and is still being made toward the understanding of the geology of Trenton Falls.>>Back to Top

Barry Cameron, Robert Titus, John L. Cisne, Charlotte J. Mehrtens, John Delano, Charles E. Mitchell, Carlton E. Brett, Gordon C. Baird

(click on the geologist's name above for more information about them and their contribution to the study of Trenton Falls.)



In the early 1960's, Barry Cameron, now Professor of Geology at Acadia University in Wolfville, Nova Scotia, began his graduate studies at Columbia University with Dr. G. Marshall Kay as his advisor. His Master's thesis documented the occurrence of transported foraminiferal assemblages in turbidites from a deep-sea core off the northeastern side of the Bahamian Platform. For his Ph.D. dissertation, Dr. Cameron chose to work on the stratigraphy and sedimentology of the lower Trentonian Series of northwestern New York and southeastern Ontario.

Having already completed some projects on modern carbonate settings, Cameron was well-prepared to address long-standing concerns regarding the nature of the lower Trenton Group. With the support and long standing expertise of his advisor, Cameron and his students at Boston University began to publish excellent summaries on the stratigraphy of the lowermost Trenton. Collectively, the research of Dr. Cameron and his students Stephen Mangion and Robert Titus, helped to document the depositional environments of the lower Trenton, and the nature of the contact between the Black River and Trenton Groups. They also documented the paleoecology of the Rocklandian, Kirkfieldian, and basal Shermanian stages in the critical region north and northwest of Trenton Falls.



Barry Winston Cameron

Professor of Geology

Acadia University






In their 1977 paper entitled "Depositional Environments and Revised Stratigraphy Along the Black River-Trenton Boundary in New York and Ontario," Barry Cameron and Stephen Mangion published a revised view of the basal Trenton. Through detailed analysis of the faunal composition of the Selby member of the Rockland Formation (basal Trenton Group, as defined by Kay; 1935, 1937), Cameron and Mangion recognized that the Selby member in the northern New York to Ontario region had nearly the same fauna as the underlying Watertown limestone (uppermost Black River Group) and shared many lithologic similarities to it as well. When they traced the Selby to the southeast into the southern Black River Valley region, just north of Trenton Falls, they noticed that the Selby began to pinch out, so that at Trenton Falls the Selby was no longer present. In their analysis, this observation was explained by the fact that the overlying Napanee Limestone had overlapped the Selby during the initial Trenton Limestone representing shoaling conditions through deeper shelf conditions in the Sugar River Limestone.




In many respects, their work was the first to document the basal disconformity of the Trenton Group. They concluded that the Black River-Trenton unconformity was greatest in the Mohawk River Valley and progressively transitioned to near conformity in the northern New York to Ontario region.

In addition to his stratigraphic studies, Cameron published some reports on the oldest known (at the time) predatory gastropod borings on brachiopods from the Trenton Group. His studies (Cameron, 1967) of these Rocklandian brachiopods demonstrated that the nearly spherical borings in the shells of Dalmanella rogata, were clearly similar in size and shape to gastropod borings from modern species. Today we recognize specimens of brachiopods and echinoderms with similar structures back as far as the Cambrian (and possibly earlier; Kowalewski et al., 1998). Cameron's studies helped to document this mode of carnivory in the Ordovician.>>Back to Top


Robert Titus a native of New Jersey began his academic career interested in general agriculture and graduated from Rutgers University in 1968. Immediately following the completion of his Bachelor's degree, Titus began graduate studies at Boston University under the tutelage of newly established professor Barry Cameron, where he earned both a M.S. and Ph.D. Influenced by the enthusiasm and knowledge of his primary advisor Dr. Cameron, Robert Titus soon established himself as a knowledgeable and very able researcher and by 1974 completed his dissertation entitled “Fossil Communities and Paleoecology of the Medial Ordovician Kings Falls and Sugar River Limestones (Trenton Group) of Northwestern and Central New York.”

This study, and a series of subsequent studies resulting from this one, provided a detailed re-examination of two of the basal Trenton formations and their associated faunal compositions. Through detailed high-resolution outcrop bedding plane faunal sampling, Titus expanded upon stratigraphic studies of co-student Stephen Mangion and advisor Barry Cameron, and provided the first paleoecological “community-level” study for the Trenton. Titus's research showed the development of four different communities within the two formations. These included the Triplecia cuspidata and Liospira sp. communities of the lower and upper Kings Falls Formation, and the Encrinurus cybelliformis and Trematis terminalis communities of the lower and upper Sugar River Formation. Moreover given the upward change in relative faunal compositions, Titus considered the succession to record an change out of shallow environmental conditions in the base of the Kings Falls through deeper water environments in the Sugar River.


"Fig. 2. Generalized correlation chart of Black River and lower Trenton groups from the central Mohawk River Valley in New York to southeastern Ontario.... Generalized paleoenvironmental framework is shown on the right hand column."

from: Cameron and Mangion, 1977





Robert Titus

Professor of Geology

Hartwick College


Subsequent to the completion of his degree, Titus took a job teaching at Hartwick College in central New York State where he continued his research on the Trenton, extending his studies into the middle and upper Trenton Group. He traced several communities through those strata, advocated facies interpretations throughout the Trenton, and recognized broadly transgressive and regressive patterns through the Trenton sequence. Titus was also able to document several species to species evolutionary events in the genera Ectenocrinus and Sowerbyella and related these to his facies patterns.

Titus, like his advisor, used his knowledge of the Trenton for the inspiration and education of his many students. His many contributions to professional publications, New York State Geological Association Field Guidebook publications, and international paleontologic-based field trip conferences represent a significant contribution to the understanding of the Trenton Limestone.>>Back to Top





Like Robert Titus, John Cisne completed his undergraduate and graduate education during the Vietnam War era with the completion of a B.S. in 1969 from Yale University and a Ph.D. in 1973 from the University of Chicago. Unlike Titus, however, Cisne's undergraduate education at Yale introduced him to paleontology early in his academic career. While at Yale, Cisne had the good fortune of being associated with Yale Peabody Museum and the legacy and collections of the great Charles E. Beecher, a turn of the century paleontologist who had worked on trilobites of the Upper Ordovician. Upon leaving Yale, Cisne's graduate research projects focused on the study of the internal anatomy and population dynamics of the Ordovician trilobite Triarthrus eatoni. Moreover his Ph.D. studies at Chicago extended beyond the simple study of trilobite anatomy and extended into evolutionary patterns and overall phylogeny of arthropods.

In the same year he completed his dissertation and published the results of his study on Triarthrus, Cisne was hired by Cornell University, where his research emphasis on Upper Ordovician trilobites from central New York allowed him the opportunity to expand his studies into aspects of the ecology of trilobites and associated faunas. Cisne's investigations soon focused on the paleoecologic implications for the distribution of the famous Trenton Limestone faunas across transects from the Trenton Falls type sections eastward into the Taconic Foreland Basin. Perhaps spurred on by initial investigation of lower Trenton paleocological studies by Titus, Cisne's studies integrated the concepts of paleoecology and community correlation or “coenocorrelation” to establish a more rigorous statistical test of environmental gradients recorded through the distribution of fossil taxa.





John L. Cisne

Professor of Geology

Cornell University


Triarthrus sp.


Between 1978 and 1982, Cisne, his students, and colleagues presented a number of talks and published several studies relating the use of gradient analysis of fossil communities to the stratigraphy of the Trenton Limestone. In the process of documenting the preserved record of environmental gradients, Cisne's research ultimately provided insights into wide-variety of geological investigations of the Upper Ordovician including: high-resolution geographic and evolutionary patterns of variations of species, chemical paleoceanography, paleobathymetry, and the study of sea-level change and paleoclimatic change in the Mohawkian-aged Taconic Foreland Basin. Moreover, Cisne's interest in the Trenton Limestone and depositional patterns associated with epeiric sea sedimentation led to studies on synthetic stratigraphy and the mechanics of sedimentary basins including the Taconic Foreland.

Ultimately Cisne's Trenton studies not only provide additional information regarding the natural history of the Trenton Limestone, but his Trenton-based studies provided additional insight into oceanography of epeiric platforms, climatic change, structural evolution of cratons and foreland basins, as well as statistical paleontology. As such his studies contribute significantly to modern geoscience research and it is clear that the Geology of Trenton Falls has been an inspiration for him. >>Back to Top


Gradient Analysis of Fossil Communities from Trenton Falls to Spraker's New York and their relationship to graben structures.

from: Cisne et al., 1982


Although born in Long Island far from the Paleozoic Rocks of central and northern New York, Charlotte Mehrtens was introduced to them during her undergraduate studies at SUNY Plattsburgh where she completed her bachelor's degree in 1974. Having been located in the heart of Middle and Upper Ordovician rocks of northern New York and southern Quebec, her interest was sparked by many aspects of the geology of the Mohawkian-aged (Middle Caradocian) carbonates in the region including the Trenton, Black River, and underlying Chazy Limestones. As a result, her graduate studies at the University of Chicago, under the supervision of A.M. Ziegler, focused on paleoenvironmental conditions impacting the development of the carbonate succession preserved in southern Quebec.

After graduating in 1979 from the University of Chicago, Charlotte Mehrtens took a teaching position at St. Lawrence University in northern New York State where she taught for three years before moving to a position at the University of Vermont at Burlington. These moves put her back in close proximity to the rocks that she had become so familiar and continued to expand upon her previous studies. Her research emphasis on sedimentary processes, depositional environments, and shelf evolution of the northern New York, to southern Quebec regions continued to provide detailed evidence for the impact of the Taconic Orogeny on the sedimentation on the cratonic margin of the northeastern United States and Canada. Moreover, based on the association of the Middle to Upper Ordovician rocks of her study region with those of the Mohawkian type sections in central New York, Mehrtens involved a portion of her research activity on questions regarding sedimentary processes and the evolution of depositional environments of this region as well. Through a series of New York State Geological Association Guidebook articles, and an AAPG publication, her research highlighted the occurrence of turbidite deposits within the upper Trenton Limestone, described their detailed sedimentology, and emphasized their implications for the evolution of the Trenton Shelf from a passive carbonate margin to distally steepened foreland basin.




Charlotte J. Mehrtens

Professor of Geology

University of Vermont, Burlington


Having approached the study of the Trenton Limestone from a sedimentologic perspective, rather than a purely paleontologic one, Mehrtens' research was unique and provided additional insights, questions, and dilemmas regarding the depositional history of the Trenton Limestone in its type section. Moreover, some of her most important contributions in this area relate to the integration of sedimentary and stratigraphic records from the northern New York /southern Quebec region to with those of the type Mohawkian strata.

Although, Mehrtens is an established researcher with many accomplishments (not limited to the Ordovician), she too has been an avid teacher and advisor to many students during her tenure. Like many of the modern geologists discussed herein, working on the Trenton Limestone and related rocks has been an inspiration not only in their own education and research agendas, but also to their curriculum development as well. Teaching courses on carbonate sedimentology, carbonate petrology, basin analysis, paleogeography, stratigraphy and sedimentology, plate tectonics, as well as historical geology have undoubtedly benefited from her experience with the Trenton and equivalent rock units. >>Back to Top



Bouma-Style Turbidite Composition from the Denley and Dolgeville Formations

from: Mehrtens, 1988


John W. Delano (Ph.D. SUNY Stony Brook, 1977) is currently the Distinguished Teaching Professor of Geology in the Department of Earth and Atmospheric Sciences at SUNY Albany. Given this prestigious title his contributions to geoscience and geoscience education go without saying, but of particular importance in the context of this website, are the research contributions he has made to the understanding of the Trenton Limestone.

Although not a stratigrapher by education, John Delano has contributed immensely to the stratigraphic problems of the Trenton Limestone. Using petrological and geochemical techniques for analyzing individual mineral grains from volcanic ash beds (K-bentonites), Delano and his students have been able to correlate individual volcanic ash beds between the carbonate platform environments represented by the Trenton Limestones and those of deeper water shale environments of the Utica Group. In a series of publications and professional meeting talks: Delano and colleagues (1990, 1994), Goldman and colleagues (1994), and Mitchell and colleagues (1994), Delano 's rigorous techniques provided the most up-to-date, high-resolution correlations between these problematic regions. When integrated with biostratigraphic data collected by Charles Mitchell and his students, it was possible to extend graptolite biostratigraphic zonations from the Utica Group Shales laterally up-dip into shallower water Trenton Limestones. By using the rapidly deposited K-bentonites, it was thus possible to constrain the relative timing and age of limestone and shale deposition in the Taconic Foreland Basin and provided a more accurate chronology of the evolution of the cratonic margin during the Upper Ordovician.

Delano 's recent research efforts have been focused on aspects of Precambrian geology, astrogeology, and geochemical techniques. His pioneering efforts and research methodologies for geochemically fingerprinting of Trenton age volcanic ash layers represents a significant advancement in the understanding of the Trenton Limestone, its depositional history, and broader geological context. Without the contributions of Delano and his students, subsequent studies on the Trenton would have been difficult if not nearly impossible to achieve. Delano and his students are recognized for their outstanding research contributions to the geology of the Trenton Limestone and Trenton Falls. >>Back to Top





John W. Delano

Distinguished Teaching Professor of Geology

State University of New York at Albany


Charles Mitchell was born in the Cincinnati, Ohio region. At an early age he was attracted to the geology and paleontology of the richly fossiliferous and world-renowned Cincinnatian rocks (Late Ordovician) of that area. Luckily, Mitchell was able to attend college at Ohio State where he began formal research on the paleontology of Ordovician rocks. Through his association with two important Ordovician biostratigraphers, Professors Walt Sweet and Stig Bergström, Charles Mitchell was soon indoctrinated into the paleontology of graptolites and their combined use with conodonts for biostratigraphic investigation. After obtaining a M.S. degree at the University of Western Ontario in 1978, Mitchell went on to Harvard University where he completed a dissertation on the astogeny and phylogeny of the Diplograptina (Graptoloidea) in 1983.

Having established himself as a graptolite paleontologist and biostratigrapher during his graduate studies, Charles Mitchell's research agendas have continued to focus on the paleobiology, systematics, and evolutionary history of graptolites and their implications for correlation of Ordovician rocks. Mitchell's research on graptolites has expanded to encompass various stratigraphic methods for the purpose of developing detailed stratigraphic frameworks for interpreting the history and evolution of sedimentary basins. The recent research contributions made by Charles Mitchell and his students at SUNY Buffalo, toward the investigation of the Trenton Limestone and associated Utica Group Shales, is herein recognized.

Like Gordon Baird and Carlton Brett (see below), Charles Mitchell has been a consistent contributor to the geological investigation of the Trenton Group during the last decade. Mitchell, with his students and a number of colleagues, has approached the study of Mohawkian strata through the application of a broad range of modern paleobiologic and modern stratigraphic techniques (see collaborative publications with John Delano, Dan Goldman, Carlton Brett, and Gordon Baird). Most recently however, and perhaps most important to the





Charles Emerson Mitchell

Professor of Geology

State University of New York at Buffalo



overall discussion of the geology of Trenton Falls and the Taconic Orogeny, was his influential role in the assembly of a special volume entitled “Taconic Convergence: Orogen, Foreland Basin, and Craton”, together with colleague Robert Jacobi, also of SUNY Buffalo. Collectively the chapters of this special volume (2002) represent some of the most up-to-date assessments of the evolution of the Laurentian Craton, Trenton Shelf, Taconic Foreland Basin, and Orogenic Center for this period of the Upper Ordovician. Included within this edited volume, Jacobi and Mitchell (2002) have an additional paper that documents the geodynamic/tectonic changes associated with the end of Trenton deposition and migration of the Taconic Foredeep Basin into central New York.

These publications constitute an integrated investigation of Ordovician history and promote a greater understanding of the history of the Earth and its biosphere. Moreover, because of his expertise and research experience with the Trenton, Charles Mitchell and his collaborative research projects are herein recognized as an important contribution to the development of this website. >>Back to Top



Representative Ordovician Diplograptid Graptolites

from: Mitchell, 1983


As a life-long fossil afficionado, admirer of natural history, and professional paleontologist, Carlton Brett has become synonymous with the Devonian, Silurian, and Ordovician rocks of New York State. Now located in the Ordovician capital of the world ( Cincinnati, Ohio ), Carlton Brett began his professional paleontologic career well before he could actually drive. As a young student on Grand Island ( Niagara Falls ) New York, Brett was eager to collect and investigate fossils from the Silurian exposures along the Niagara Gorge. His great enthusiasm for paleontology led to numerous research opportunities at the Buffalo Museum and at SUNY Buffalo where he received both his Bachelor's (1973) and Master's degrees (1975). Carl Brett published numerous papers on Silurian echinoderms, and went on to complete his dissertation at the University of Michigan. He returned to western New York in the fall of 1978 to accept a position at the University of Rochester, where for 20 years his research activities focused on all aspects of the paleontology and stratigraphy of Devonian, Silurian, and Ordovician rocks of New York State.

Through his interest in rare echinoderms, Brett became interested in the paleontologic and stratigraphic history of the Ordovician rocks of Kirkfield , Ontario . Brett and colleagues in Ontario published several manuscripts on these rocks, their depositional histories, and on the “Kirkfield Echinoderm Faunas.” Through his association with these rocks, together with colleague Gordon Baird (see below), Brett began investigations on equivalent strata in central New York State. By the beginning of the 1990's Carlton Brett, Gordon Baird and their students began to publish a series of papers discussing some of the enigmatic, decades-old stratigraphic and paleontologic problems associated with the Upper Ordovician rocks of the Mohawk Valley. The culmination of these research investigations is represented by their recent contributions to the Mitchell and Jacobi edited volume entitled: “Revised stratigraphy of the Trenton Group in its type area, central New York State: sedimentology and tectonics of a Middle Ordovician shelf-to-basin succession” (Brett and Baird, 2002), and “Indian Castle Shale: late synorogenic siliciclastic succession in an evolving Middle to Late Ordovician foreland basin, eastern New York State” (Baird and Brett, 2002).






Carlton Elliot Brett

Professor of Geology

University of Cincinnati







Revised Upper Mohawkian-Lower Cincinnatian Chronostratigraphy of Central New York State

from: Brett and Baird, 2002








In addition to his contributions toward a revised chronostratigraphy based on event, litho-, and biostratigraphic observations, Brett has also been a contributor to the restudy of the paleontology of the Walcott-Rust Quarry. This resulted in the publication of “Walcott-Rust Quarry: Middle Ordovician Trilobite Konservat-Lagerstätten” (Brett et al., 1999). A major focus of this research was the use of the taphonomy of fossil specimens as indicators of depositional history. Brett and colleagues used the degree of disarticulation, or lack thereof, to establish constraints on the physical processes involved in the deposition of the Trenton limestones. Drawing on aspects of his research on modern shelf and slope depositional environments, Brett has been able to document the exquisite preservation of trilobites, echinoderms, and a variety of other taxa within the Rust Quarry Beds, and within much of the Trenton. It is clear that many of these organisms were smothered alive as the result of catastrophic and rapid burial events that punctuated rather long periods of slow sedimentation, condensation, and low background depositional energy.

Brett's research on the Trenton has used a broad, integrative approach to modern stratigraphic study, combined with the finest-scale, bed-level sedimentary and taphofacies analysis. Broad-ranging collaborative projects from both the modern and all eras of the Phanerozoic, have been undertaken by Brett, his colleagues and his students, always with great attention to detail. Brett has thus been well-prepared to generate new hypotheses and new ideas to investigate a range of old and new problems for the Trenton Limestone. For his review and professional commentary on this website, his participation is gratefully acknowledged. >>Back to Top



Gordon Baird, another New Yorker by birth, was also an early afficionado of rocks, and fossils. Gordon Baird found his early academic career on the plains of the Midwest where his undergraduate education at Earlham College introduced him to the famous Mazon Creek Formation. As another example of a fossil lagerstätte, the Mazon Creek and its iron siderite concretions helped to preserve a range of soft-bodied tissues from invertebrate (and vertebrate) organisms that are normally absent from the fossil record. Baird's did early research on the famous nodules and the detailed sedimentologic and stratigraphic analysis of the deposits. His dissertation research at the University of Rochester focused on the recognition of unique stratigraphic horizons and their evidence for mineralogical and organic enrichment, authigenic crystallization, and early cementation as recorders of events and discontinuity surfaces within the rock record. The recognition of these key surfaces has been carried over to collaborative studies with colleague Carlton Brett on both the Devonian Hamilton Group and the Mohawkian and Cincinnatian rocks of the type regions.

Dr. Baird's research emphasis on the Trenton has been toward the documentation and correlation of key stratigraphic surfaces recording condensation, sediment starvation, submarine erosion, fossil epiboles, and hardground development. With an incredible knack for picking just the right interval, Gordon Baird's “eye” for stratigraphic studies has been a strong asset, including to his most recent research efforts on the Trenton Limestone and its siliciclastic equivalents. His most recent publications, have also helped delineate a large number of altered volcanic ash deposits within the Trenton and Indian Castle Shales (Utica Group). In the 2002 publications: Baird and Brett; and Berkley and Baird, he has documented geochemical signatures of individual K-bentonites as well as unique sedimentologic and petrographic characteristics of others which show evidence for a variety




Gordon C. Baird

Professor of Geology

State University of New York at Fredonia



of submarine hydraulic processes, and early cementation events (normally lost during diagenesis). These uniquely preserved K-bentonites have long been overlooked by other researchers; however, the preservation of unique mineral textures and crystallographic morphologies provide unique signatures useful in correlation. As a result, Baird's studies have helped elucidate a series of high-resolution correlations (sub-meter scale, <100,000 year durations) for the upper Trenton interval. The resulting frameworks have helped to constrain patterns of foreland basin tectonic development, migration of foreland basin components, as well as the timing and depositional signatures of eustatic sea-level fluctuations within the shelf-to-basin environments of central New York State.

As with all of the researchers above, unique strengths and research perspectives provide Gordon Baird with a strong set of observational and analytical tools. These enable him to pose critical hypotheses, and also use deductive and reasoning skills to test them. Gordon Baird's research accomplishments are noteworthy and exceptionally valuable to the understanding of the stratigraphy of the Trenton Limestone, and the tectonic evolution of the basin within which these rocks were deposited. >>Back to Top


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