EXAMPLES OF FIELD PROJECT ASSIGNMENTS
IN
SEDIMENTARY GEOLOGY AT SUNY ONEONTA
James R. Ebert
Earth Sciences
Department
(607) 436-3065;
Ebertjr@oneonta.edu
1992 |
A) Anatomy of an Unconformity ♦ B) Microstratigraphic
Correlation of Closely Spaced Outcrops and K-Bentonites |
1997 |
|
1999 |
|
2001 |
Contacts and Correlation of upper Helderberg
formations from Schoharie
to Sharon Springs |
2003 |
Microstratigraphy and Depositional Environments of the Manlius
Formation in the Howe Cave Quarry |
2005 |
Depositional
Environments and Stratigraphic Markers in the Lower Helderberg Group
♦ ♦ |
NOTE: Sections under these headings are the actual assignment sheets given to the students. Lists of references originally accompanied these assignment sheets, but in the interest of conserving space, they have been omitted. ♦ = Presented at Northeast
GSA. Reference to abstract follows project description. |
1992 A: ANATOMY OF AN
UNCONFORMITY
INTRODUCTION
Without question, the most significant geologic
boundary in central
Following
glacial erosion, the surface was buried beneath glacial and glacio-fluvial
and glacio-lacustrine sediments. It is likely that
some of these sediments were removed and additional erosion took place during
multiple glacial advances. The final glaciation
blanketed the unconformity surface with a thin to absent veneer of sediments in
upland regions and along valley walls and a much thicker accumulation in
valleys. Clearly, there is a great deal of relief on this unconformity surface.
Although the general geometry of the unconformity is known (to some extent it
mirrors present topography), specific details are sparse because the surface is
buried beneath Pleistocene and Holocene sediments.
DEVONIAN - PLEISTOCENE
UNCONFORMITY IN THE ONEONTA AREA
On
the east end of Oneonta, Devonian bedrock is dramatically exposed in the
faceted spur that is opposite the entrance to the Pyramid Mall. Indeed, this
mall takes its name from the rock exposure: Pyramid Rocks. Less than one
kilometer west of Pyramid Rocks, Devonian rocks are also clearly exposed in
Glenwood Creek. It seems likely that little erosion of the bedrock has taken place
since the last glacial retreat, some 10,000 years ago. If we accept this simple
assumption, the present topography north of Route 7 and east of Glenwood Creek
approximates the unconformity surface.
South
of Route 7, the geometry of the unconformity is much less clear. In
During
the summer of 1991, John Kucewicz and associates
conducted resistivity and seismic studies near our
proposed study area. The results of these studies (Kucewicz,
1992) suggest that the depth to bedrock is much shallower than indicated by
Cohen (1991) immediately south of Route 7 and that it may even be expressed
topographically in the form of a terrace-like feature on the wall of the valley
and perhaps in the form of sinuous ridges on the south side of this
terrace-like feature. Conventional interpretations of these landforms ascribe a
glacial origin and imply that bedrock is hundreds of feet below the surface.
FIELD METHODS AND DATA
COLLECTION
Over the
next several weeks, we will conduct various geophysical surveys in the field
area in an attempt to discern the geometry of the Devonian - Pleistocene
unconformity. Gravimetric and seismic surveys will be the primary tools that we
will use. Surveying techniques will also be employed to accurately locate data
points and to enable formulation of various correction factors, particularly
for the gravimetric survey. Results of the gravimetric survey will be directly
comparable to the results of Cohen (1991) if we can accurately tie our base
station to his.
If
time permits, we will also attempt a resistivity
survey which will allow us to compare directly to the work of Kucewicz (1992) in adjacent areas. Following collection and
analysis of geophysical data, we will also examine samples from a well drilled
within the study area and use this data as a test on the accuracy of our
geophysical data.
The
compilation of geophysical data, well data and perhaps data from Cohen (1991)
and Kucewicz (1992) will provide the basis for
interpretation of the geometry of the unconformity in the study area. We will
also discuss processes responsible for this geometry if the data is
sufficiently intriguing. A final report comprising all raw and corrected data,
cross sections, maps and narrative will serve as the basis for evaluation of
this project. If the results warrant, we will prepare an abstract for
submission to the Northeastern Section of the Geological Society of America.
The abstract deadline is November 24 and the meeting will be held March 22 -
24, 1993 in
NOTE: This project resulted in an oral presentation at a Northeast GSA
Conference. Undergraduate co-authors are underlined and boldfaced.
Kucewicz, J., Jr., Ebert, J., Rasquin,
C., Sherman, R., Nethaway, R., Gardner, J., Milunich,
K., Weber, J., Wohlford, T., Franz, J., Brillon, S.,1993, Unusual Configuration of the
Devonian-Pleistocene Unconformity in the Susquehanna Valley, Oneonta, New York:
Evidence for a Subglacial Meltwater
Inlet to Glacial Lake Otego: Geological Society of America, Abstracts with
Programs, v. 25, no. 2, p. 65.
1992 B: MICROSTRATIGRAPHIC CORRELATION OF CLOSELY
SPACED OUTCROPS AND K-BENTONITES
Recent studies have
documented multiple K-bentonite beds in the Kalkberg Formation (Helderberg
Group, Lower Devonian) at
Lower Helderberg strata are
exposed in a series of roadcuts along
Reporting and Evaluation: The compilation of
measured sections and their correlation will constitute the final report for
Project 2. A brief one to two page paper which discusses the correlation should
also be included.
1997: FACIES CHANGE OR
UNCONFORMITY?
INTRODUCTION
For decades, the Devonian
strata of
Prominent exposures of
Lower and Middle Devonian rocks occur across much of east central
For the next several weeks,
we will be measuring stratigraphic sections at
ASSIGNMENT
Working in small teams, you
will measure the stratigraphic sections at
Although field measurements
and observations will be garnered as teams, each of you will be responsible for
submitting correlations and reports as individuals. Measured sections should
include descriptions of: lithology, texture, sedimentary structures, biogenic
structures, fossils, bedding thickness and geometry, prominent lithologic breaks
and designations of stratigraphic units of formational or smaller rank. Your
data for each location should be summarized in the form of neatly drafted
columnar sections at a vertical scale of 1:50, that is, one centimeter on the
paper will represent 50 centimeters of outcrop. Lithologies should be indicated
by standard symbols.
Once the sections are
drafted, you will prepare a correlation of the sections. The columns should be
spaced proportionately to their actual geographic distance. Note that horizontal
scale need not have any direct relationship to the vertical scale of the
columns.
A brief written report
should also accompany your correlation. Reports should include a description of
the stratigraphic changes between sections, a section that focuses specifically
on the nature of contacts between units and a discussion of any difficulties
encountered in correlation and interpretations of the geologic history that is
recorded at and between these sections.
1999:
RIPPLES IN THE HOWE CAVE QUARRY
FIELD
PROJECT: Depositional Processes in the Thacher Member of the Manlius Formation
(Helderberg Group, Upper Silurian – Lower Devonian) in the
The Siluro-Devonian
Helderberg Group (Přídolí – Lochkovian) has been
widely cited as an archetype for Paleozoic carbonate sequences (e.g., Laporte,
1967, 1969) and deposition in epeiric seas (e.g., Prothero, 1990). Despite this
illustrious history, there are many questions that remain unanswered from this
fascinating interval. Current research by Ebert and Matteson (in progress) is
indicating that there may be a need to revise the classic stratigraphic
framework of Rickard (1962). Because this stratigraphic reconstruction laid the
groundwork for Laporte’s (1969) interpretations of depositional environments of
the lower Helderberg Group and the Manlius Formation in particular (Laporte,
1967), opportunities may exist to further refine Laporte’s interpretations in a
new context.
The inactive Howe Cave
Quarry, located near
For the next couple of
months, we will conduct field studies in the Howe Cave Quarry with special
emphasis on the Thacher Member of the Manlius Formation. After one or two weeks
of making preliminary observations and formulating questions based on these
observations, we will define research projects that will attempt to answer some
of these questions. As you are formulating your questions, try to think of what
types of data must be collected to address these questions. Our focus will be
on sedimentary processes and depositional conditions, so you should pay
particular attention to sedimentary structures. However, don’t discount the
significance of lithology, lithologic changes and the fossils in the outcrop.
Presentation of the results
of your investigations will be in the form of a written report which details
your descriptions and interpretations. You will share a brief summary of your
report with the rest of the class and we will discuss your results. Be prepared
to defend your interpretations!
Depending on the outcomes
(if any!) of your projects, we may prepare one or more abstracts to submit for
presentation at the annual meeting of the Northeast Section of the Geological
Society of America. The abstract deadline is near the end of the semester, but
the conference is in the spring (mid-March). Because GSA is in the semester
that follows completion of this course, participation in any GSA-related
activities (abstract submission, preparation of poster or PowerPoint for talk
and presentation at the conference) will be strictly voluntary. Please keep in
mind that your project may be worthy of publication so you should strive for
excellence and thoroughness!
NOTE: This class
project resulted in presentation at the 2000 Northeast GSA conference with all students
in the class as co-authors on the abstract (student names are boldfaced).
Ebert, J.R., Deats, M.D., Chartier, M.G.,
2001:
CONTACTS AND CORRELATION OF UPPER HELDERBERG FORMATIONS FROM SCHOHARIE TO
INTRODUCTION
The Siluro-Devonian
Helderberg Group (Přídolí – Lochkovian) has been
widely cited as an archetype for Paleozoic carbonate sequences (e.g., Laporte,
1967, 1969) and deposition in epeiric seas (e.g., Prothero, 1990). Despite this
illustrious history, there are many questions that remain unanswered from this
fascinating interval. Recent stratigraphic work in the lower Helderberg Group
(Ebert and Matteson, 2001a,b) has called into question the traditional
stratigraphic framework of Rickard (1962) which served as a central foundation
for Laporte’s (1969) interpretations of depositional environments. The work of
Ebert and Matteson suggests that contacts between stratigraphic units are
unconformable rather than gradational changes of facies as Rickard suggested.
If these recent stratigraphic reinterpretations are correct, then a need exists
to re-examine all stratigraphic relationships in the Helderberg Group.
The Becraft Formation, a
coarse crinoidal grainstone in the upper Helderberg Group, is one of the most
distinctive units within the group (Ebert, 1983, 1987). The Becraft is well
exposed in two large road cuts on opposite sides of
Results from your field
investigation may be supplemented by analysis of samples collected from the
outcrops. If samples require processing (e.g., cutting,
polishing, making thin sections, etc.), I will assist you in this preparation
and in the laboratory examination of your samples.
Presentation of the results
of your investigations will be in the form of a correlation of the measured
sections of the two outcrops. This correlation will be accompanied by a written
report which details your descriptions and interpretations. Depending on the
originality of your results and the strength of the data supporting your
interpretations, we may prepare abstracts to submit for presentation at the
annual meeting of the Northeast Section of the Geological Society of America.
Because GSA meets in March, well after the end of this course, participation in
any GSA-related activities (abstract submission, preparation of poster or talk
and presentation at the conference) will be strictly voluntary. Your projects
may culminate in publication and presentation, so you should set and maintain
the highest standards for your work!
NOTE: Although this project did not result in publication, it did
discover a new K-bentonite at the contact between two sub-units of the Becraft
Formation.
2003 – MICROSTRATIGRAPHY AND DEPOSITIONAL ENVIRONMENTS OF THE MANLIUS FORMATION IN THE HOWE CAVE QUARRY
FIELD
PROJECT: Microstratigraphy and Depositional
Environments of the Manlius Formation (Helderberg Group, Upper Silurian – Lower
Devonian) in the
The Siluro-Devonian
Helderberg Group (Přídolí – Lochkovian) has been
widely cited as an archetype for Paleozoic carbonate sequences (e.g., Laporte,
1967, 1969) and deposition in epeiric seas (e.g., Prothero, 1990). Despite this
illustrious history, there are many questions that remain unanswered from this
fascinating interval. Recent studies by Ebert and Matteson (2003a, b) has
proposed a significant revision to the classic stratigraphic framework of
Rickard (1962). Because Rickard’s reconstruction laid the groundwork for
Laporte’s (1969) interpretations of depositional environments of the lower
Helderberg Group and the Manlius Formation in particular (Laporte, 1967),
opportunities may exist to further refine Laporte’s interpretations in a new
context.
The inactive Howe Cave
Quarry, located near
For the next couple of
months, we will conduct field studies in the Howe Cave Quarry with special
emphasis on the Thacher Member of the Manlius Formation. Our focus will be on
sedimentary processes and depositional conditions, so you should pay particular
attention to sedimentary structures, lithology and the types and distribution
of fossils in the Thacher. Results from your field investigation may be supplemented
by analysis of samples that you collect. You will be instructed in the
preparation of polished and/or etched slabs and thin sections as the need
arises. Also, you will be guided in observation of these prepared samples with
binocular and petrographic microscopes to supplement your field observations.
Presentation of the results
of your investigations will be in the form of a neatly drafted stratigraphic
column with an accompanying written report which details your descriptions and
interpretations. You will share a brief summary of your report with the rest of
the class and we will discuss your results. Be prepared to defend your
interpretations!
Depending on the outcomes
(if any!) of your projects, we may prepare one or more abstracts to submit for
presentation at the annual meeting of the Northeast Section of the Geological
Society of America. The abstract deadline is near the end of the semester, but
the conference is in the spring (mid-March). Because GSA is in the semester
that follows completion of this course, participation in any GSA-related
activities (abstract submission, preparation of poster or PowerPoint for talk
and presentation at the conference) will be strictly voluntary. Please keep in
mind that your project may be worthy of publication so you should strive for
excellence and thoroughness!
2005: DEPOSITIONAL ENVIRONMENTS AND STRATIGRAPHIC MARKERS IN THE LOWER
HELDERBERG GROUP
FIELD
PROJECT: Depositional Environments and Stratigraphic Markers in the Lower
Helderberg Group
The Siluro-Devonian
Helderberg Group (Přídolí – Lochkovian) has been
widely cited as an archetype for Paleozoic carbonate sequences (e.g., Laporte,
1967, 1969) and deposition in epeiric seas (e.g., Prothero, 1990). Despite this
illustrious history, there are many questions that remain unanswered from this
fascinating interval. Recent stratigraphic work (Ebert and Matteson, 2003a,b;
2005) has called into question the traditional stratigraphic framework of
Rickard (1962) which served as a central foundation for Laporte’s (1969)
interpretations of depositional environments. If the recent stratigraphic
reinterpretations are correct, then perhaps the time is also ripe to re-examine
the sedimentology of these classic stratigraphic units.
Several large road cuts on
Interstate 88 just west of the Schoharie exit expose, almost completely, all
the units of the Helderberg Group that are present in the Schoharie and
Cobleskill valleys. The easternmost outcrop will be the focus of our
investigations. This road cut exposes the Upper Silurian Brayman Shale at its
base. The Brayman is disconformably overlain by the Cobleskill Limestone, which
is, in turn, overlain by the Rondout Formation. Two distinctly different
members of the Manlius Formation follow: The Rondout is overlain by the Thacher
Member of the Manlius Formation which is succeeded by the Green Vedder Member
(informal). The Green Vedder is bounded below by the Clockville Unconformity
and is truncated above by the Terrace Mountain Unconformity. The Dayville
Member of the Coeymans Formation overlies the Terrace Mountain Unconformity and
is truncated above by the Howe Cave Unconformity. The highest unit in the
outcrop is the remainder of the Coeymans Formation, which is mapped as Ravena
Member, but may also include parts of the Deansboro Member. Other road cuts
along I-88 expose the younger Kalkberg, New Scotland and Becraft formations of
the middle and upper Helderberg Group. The Becraft is cut by the widespread
Wallbridge Unconformity and is overlain by the Oriskany Sandstone and other
units of the Tristates Group.
For the next couple of
months, we will conduct field studies at the I-88 east outcrop through the
courtesy of the New York State Department of Transportation, from whom I have
obtained a work permit to allow us to work along the interstate. You will be
divided into teams of two, with three teams investigating the Thacher Member of
the Manlius Formation and two teams examining the Coeymans Formation. You are
to observe and record (via a graphic measured section) lithologies, sedimentary
structures, biogenic structures, fossils, unique taphonomic occurrences and any
other features that will assist you in interpreting the depositional processes
and environments that are recorded by these units. In addition, you should also
be on the lookout for any distinctive sub-units which may aid in regional
correlation. Likewise, you should pay particular attention to contacts between
major stratigraphic units and between any sub-units that you identify.
Results from your field
investigation may be supplemented by analysis of samples collected from the
outcrop. You will be instructed in the preparation of polished and/or etched
slabs and thin sections as the need arises. Also, you will be guided in
observation of these prepared samples with binocular and petrographic
microscopes to supplement your field observations.
Presentation of the results
of your investigations will be in the form of a written report which details
your descriptions and interpretations and in a poster which will be shared with
the class in an informal ‘poster session.’ Please note that if the results of
your investigations are of sufficient merit, we may prepare abstracts to submit
for presentation at the annual meeting of the Northeast Section of the
Geological Society of America. The deadline for abstract submission is December
13, one day before our final exam/meeting. Northeast GSA meets in March in
NOTE: This class
project resulted in two poster presentations at the 2006 Northeast GSA conference with all
students in the class as co-authors on the abstracts (student names are
boldfaced).
Ebert, J.R., Miller, J., Nierenberg, D.,
Matteson, D.K.,