Stratigraphy and Paleoenvironments of the Red Hill Site Near Hyner

The Pennsylvania State University

The Graduate School

College of Earth and Mineral Sciences

STRATIGRAPHY AND PALEOENVIRONMENTS OF THE RED

HILL SITE NEAR HYNER, PENNSYLVANIA

A Thesis in

Geoscience

Daniel Adam Peterson

Submitted in Partial Fulfillment of the Requirements for the Degree of

Master of Science

May 2010

The thesis of Daniel Adam Peterson was reviewed and approved* by the following:

Mark E. Patzkowsky Associate Professor of Geosciences Thesis Advisor

Rudy L. Slingerland Professor of Geology

Russell W. Graham Associate Professor of Geosciences Earth and Mineral Sciences Museum Director

Katherine H. Freeman Professor of Geosciences Associate Department Head of Graduate Programs

*Signatures are on file in the Graduate School

ABSTRACT

The Red Hill outcrop on Route 120 near Hyner, Pennsylvania, consists of repeating cycles of

mostly fining-upward facies ranging from siltstones and lower fine massive sandstones at the base

of the cycles to mudstones near the top of each cycle. In the readily accessible portions of the

outcrop, a wide variety of vertebrate and plant material can be found. Vertebrates recognized from

Red Hill include various fishes (placoderms, chondrychthyans, acanthodians, actinopterygians, and

sarcopterygians) as well as two early tetrapods first identified at this site (Hynerpeton bassetti and

Designathus rowei). Strata at Red Hill appear cyclical and are interpreted to represent two stages of

fluvial deposition. Stage I avulsive deposits include crevasse-splay sandstone bodies and sandy

siltstone channel fills, overlain by the fossiliferous siltstones and interbedded erosional-based sandstones. These beds are overlain by simple paleosol packages that indicate Stage II avulsive deposition. High sedimentation rates on the Catskill Delta combined with regularly avulsing fluvial systems likely led not only to an excellent taphonomic setting for preserving early tetrapods, large freshwater fish, and a variety of other fossil material, but also created a highly dynamic environment in which these organisms were interacting and evolving.

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TABLE OF CONTENTS

List of Figures...... v

List of Tables…...... vi

Acknowledgements………………………………………………………………………..………. vii

Introduction……………………………………………………………………………………...….. 1

Geologic Setting…………………………………………………………………………………….. 2 Appalachian Basin and Acadian Orogeny…………………………………..…………..….....… 2 Catskill Delta……………………………………………………………………………………. 4 Red Hill…………………………………………………………………………………………. 4

Methods……………………………………………………………………………………...……... 6

Data………………………….…………………………………………………..………...…....…... 9 Lithologic descriptions…..…………..…….………………………………………..………...... 9 Facies proportions…………………………………………………………………....………... 12 Sand body geometry……..…………………………………………………………….……..... 12 Results of fossil material survey……..………………………………………………………... 16

Discussion…………………………………………………………….………………………...…. 16 Evidence for avulsive processes…………………...……………………………...……….…... 16 Further avulsion studies…………………………………………………………...…….……... 22 Circumstantial evidence supporting an avulsion model…………………………….……...….. 23 Significance for alluvial packages in the geologic record, early tetrapod evolution, and fossil prospecting…………………………………………………………………………………….. 24 Possible limitations of the Red Hill and further work………………………..…………..……. 29

Conclusion…………………………………………………………….…………………………… 30

Works Cited……………………………………………………….……………………....…….…. 32

Appendix A – Fossil sampling location data……………….………….………….………...……... 36

Appendix B – Individual fossil data………………….………………….………………….….….. 37

LIST OF FIGURES

Figure 1. Late Devonian (363 Mya). After Clack, 2002…...……………………………………… 3

Figure 2. Block diagram showing Acadian Mountains, Catskill Delta and Appalachian Basin….... 5

Figure 3. Pennsylvania map showing Red Hill outcrop………………………………………..…... 6

Figure 4. Photomosaic of outcrop with seven measured sections………...….………..………….. 13

Figure 5. Flat-based sandstone (facies F)…………………………………….……………....…… 15

Figure 6. Schematic model of Saskatchewan avulsion belt……………………………………..... 19

Figure 7. Cross section of avulsive sediments…………………………………………….……..... 19

Figure 8. Aerial photo of a trunk channel and crevasse splay in Saskatchewan………..………… 21

Figure 9. Aerial photo of Saskatchewan floodplain during avulsion……………………………... 22

Figure 10. Correlated sections showing lithofacies and avulsive interpretation ………………..... 26

Figure 11. Photomosaic and drawing of Stage I and Stage II at Red Hill………………………… 27

Figure 12. Schematic model of Stage I and Stage II deposits…………………………………….. 28

LIST OF TABLES

Table 1. Facies of lower portion of Red Hill outcrop……………………………………………... 14

Descriptions of color, texture, geometry, internal structure, contacts, and fossil material found in

the accessible lower portion of the Red Hill outcrop

Table 2. Interpretation of paleoenvironments………………………………………………….…. 25

Descriptions of facies placed in interpretive paleoenvironmental context

ACKNOWLEDGMENTS

I would like to thank Mark Patzkowsky for helping me through the rough periods and guiding me toward completion. I would like to thank my other committee members, Rudy Slingerland and

Russell Graham for their continued support and advice throughout the data-gathering and writing process. I am extremely appreciative for the help of Doug Rowe, the Red Hill site curator, who was on site nearly every day that I was, and who was an invaluable source of information on fossil locations and identifications at the outcrop. I would like to thank Ted Daeschler and Walt Cressler for talking over their thoughts on the site and my research with me. Thanks also to everyone at

Penn State who helped with my learning process including, but certainly not limited to, Doug

Edmonds, Zachary Krug, Jocelyn Sessa, James Bonelli, Matthew O’Donnell, Ellen Currano, Peter

Flemings, and Peter Wilf. I would like to thank Ray Rogers, my advisor and friend at Macalester

College who often had a useful bit of advice to help get me through. And most of all, I would like to thank my parents Mark and Julie Peterson and my sister Leah Peterson for loving, supporting and advising me through all my trials and endeavors.

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Introduction

The nature of the Late Devonian world into which the earliest tetrapods crawled is of great interest in evolutionary studies. Even so, there is still no consensus as to the environments in which tetrapods first evolved or the evolutionary impetus for leaving their aquatic habitats and venturing onto land. In the early part of last century, Alfred Romer hypothesized that the basins of the Old

Red Sandstone continent were characterized by regularly occurring semi-arid seasons that pressured the first tetrapods to migrate from drying pools to wetter, more permanent ones (1933).

The theory was widely accepted and was consistent with the general idea that redbeds are a strong indictaor of dry spells that would account for such behavior. Inger (1957) cited several studies showing that contemporary red soil beds form almost exclusively in warm, humid, rainforest-like conditions, often lacking any dry season or semi-arid conditions. He suggested that terrestrial conditions in the Late Devonian were likely far more hospitable to aquatic animals than Romer had envisioned. Orton (1954) suggested that tetrapod limbs were not, at least initially, adapted as a means of locomotion on land at all. Rather, these robust limbs were used to dig into the mud to stay cool and moist during estivation. However, certain living lungfishes (close relatives of the early tetrapods) commonly burrow into the mud with limbs distinctly dissimilar to those of early tetrapods (Clack 2002). Moreover, this leaves unanswered the question of why early tetrapods eventually became terrestrial, and what those paleoenvironments looked like.

The oldest tetrapods currently known are Obruchevichthys and Elginerpeton from the Frasnian of

Latvia and Russia (Ahlberg 1995). Both were described over a century ago, but have only recently been classified as tetrapods (Ahlberg 1995). There is still some debate as to whether

Obruchevichthys falls within or just outside of the tetrapod clade (Ahlberg 1995; Clack 2002).

These earliest tetrapods are followed in the Famennian by Acanthostega, Ichthyostega, Designathus and Hynerpeton, the last of which was discovered at the Red Hill locality near Hyner, PA (Clack

2002.) More recently, Tiktaalik, a transitional organism between the Sarcopterygians (lobe-finned fish) and tetrapods, was described in meandering stream facies from the early and middle Frasnian of Ellesmere Island, Nunavut, Canada (Daeschler et al. 2006).

Initial paleoenvironmental descriptions of Red Hill were made as vertebrate material was being discovered. These interpretations combined the general overview of the environments present on the Late Devonian Catskill Delta with specific observations of the fossil-bearing beds (e.g.

Daeschler, et al. 1994; Woodrow, et al. 1995; Daeschler 2000a, b). The prevailing interpretation of paleoenvironments at Red Hill describes the lateral migration of a large broad river channel with seasonal drying of the proximal floodplain (Woodrow et al. 1995). This interpretation of Red Hill supports the general notion that early tetrapod environments were seasonally dry in this and other previously described locations, but does not necessarily support the evolutionary model set forth by

Romer. This paper aims to examine in greater detail the sedimentary beds that contain fossils of

Hynerpeton and Designathus roweii as well as a host of lungfishes, sharks, plants and charcoal, and to provide a model for the depositional environments typical of the Hyner Late Devonian tetrapod fossil bed.

Geologic Setting

Appalachian Basin and Acadian Orogeny

The Old Red Sandstone continent, given its name for the abundance of red-colored sediments deposited there, was fully assembled by the end of the Devonian and consisted of Baltica,

Figure 1 – Paleogeography during the Late Devonian (363 Mya). After Clack, 2002.

Armorica, and Laurentia (Woodrow 1985). Just prior to the onset of the Acadian orogeny, the

Appalachian basin was an underfilled foreland basin that had been subsiding since the Late

Precambrian (Faill 1985). The Catskill Sea filled the basin and was separated from the world ocean by the Appalachian peninsula to the south and east. It joined the world ocean to the southwest and west, though it is likely that interaction was limited by an archipelago (Woodrow 1985). The northward extent of the Catskill Sea is inferred based on the occurrence of evaporites in what is now Hudson Bay, suggesting a saline bay at least this far north (Woodrow 1985). During the Early and Middle Devonian, the Appalachian basin experienced very little subsidence. As this Acadian orogenic event proceeded, the foreland basin underwent rapid subsidence, most significantly in the eastern portion in what is now Pennsylvania and New York (Faill 1997b). Specifically, estimates indicate that the subsidence rate at the Hyner locality in Clinton County, Pennsylvania increased from 5-10m/MY during the Early Devonian, to 25-50m/MY during the Middle Devonian, up to

150-175m/MY during the Late Devonian (Faill 1985). 3

Catskill Delta

The term “Catskill Delta” is generally used to describe the terrigenous sediments deposited in the rapidly subsiding Appalachian Basin during the Middle and Late Devonian, though it is apparent that not just one, but numerous river systems fed the basin with sediments from the South and East during this time (Sevon 1985; Faill 1987b). The Catskill Formation has been interpreted to comprise facies ranging from immature braided stream depositional systems in the east (Sevon

1985) to turbidite deposits in the west (Lundegard, et al. 1985). Non-marine fluvial facies of New

York and Pennsylvania, relevant to the present study, comprise grey channel sand bodies and grey to red siltstone and mudstone packages with thin (meter-scale or thinner) sandstone strata (Bridge

2000). Rivers on the lower (northwestern) portion Catskill Delta nearer to the inland sea were sinuous and migrated laterally across alluvial plains (Gordon and Bridge 1987). Levees (and possibly proximal floodplains) hosted Archaeopteris forests, while lycopsids populated wetland and lakeshore sediments (Cressler 1999). Figure 2 depicts the paleogeography of the Catskill Delta of Pennsylvania in the Late Devonian.

Red Hill

The Red Hill outcrop in Clinton County, near Hyner, Pennsylvania on Route 120 (see Figure 3 for map), is of special interest within the Catskill Delta. The outcrop consists of a roadcut approximately 1km long and contains very fine grey and reddish brown sandstone bodies surrounded by red, green and brown siltstones and mudstones. The discoveries of some of the earliest known amphibians in North America as well as a variety of fish and plant fossils have made the Red Hill outcrop an important study area.

Figure 2 – Block diagram showing Acadian Mountains, Catskill Delta, and Appalachian Basin of the present-day mid-Atlantic region of North America. (After Slingerland et al. 1989)

The rocks here belong to the uppermost member of the Catskill Formation, the Duncannon Member

(Woodrow, et al. 1995). Based on a palynological study of the outcrop, the rocks at Red Hill occur in the upper Fa2c part of the Upper Famennian stage of the upper Devonian (Traverse 2003). In one previous published analysis of the site, four lithofacies were described and briefly interpreted: red hackly-weathering mudstone, red pedogenic-mudstone, greenish-gray mudstone and very fine grained sandstone, and flat-laminated gray sandstone (Woodrow, et al. 1995). The descriptions of these facies are elaborated upon in the present study.

Figure 3 – Pennsylvania map showing location of Red Hill outcrop near Hyner along PA Route 120. Eastern end of site is located at a lat.-long. of 41 20’11.81”N and 77 39'29.45"W. Numbers indicate Interstate 80, US Route 220, and PA Routes 120 and 144.

Methods

Prior to examining the Red Hill outcrop in detail and measuring section, photographs were taken of the entire length of the outcrop with the eventual goal of stitching together a panorama view of Red

Hill. This panorama could then be used to follow individual beds and contacts from one end to the other and to show large scale geometries of the outcrop as a whole.

Starting at the eastern end of the outcrop, a digital photograph was taken of the base – the 6 accessible portion -- of the outcrop. Moving west after each photograph, an adjacent photograph was taken, with approximately one third of the frame overlapping with the previous frame. This yielded overlapping photos showing the entire fossil-bearing zone.

The photos were processed using Adobe Photoshop in order to stitch them together in a reasonably accurate way. Each photo required adjustment due to perspective before two adjacent photos could be stitched together. Because of the photographer’s perspective at ground level, parallel vertical lines converged towards the top of each photo, making it necessary to stretch the upper portion of each photo in order to eliminate overlapping errors. The photos could then be stitched together with reasonable accuracy by lining up easily recognizable features in the overlapping portions. The final product consisted of several long scrolls containing a panoramic view of the outcrop. The results of this process can be seen in Figures 4, 5, and 10.

The photomosaic aided in performing more detailed analyses of the outcrop, including measuring section and locating important sand bodies, channel fills, and previous fossil quarries. Measured sections were chosen to overlap with units previously described by Woodrow, et al. (1995), include the well-known fossil localities, and to depict the key lithologic features and changes that characterize the fossiliferous portions of the outcrop. Sections were measured at a centimeter scale using a Jacob staff and Brunton compass. Contacts between facies were marked on the photomosaic and typical samples from each facies were collected for further analysis in the lab.

For each facies, the following data were collected when possible: grain-size, sorting, shape and roundness, color, reaction to hydrochloric acid, sedimentary structures, geometry of beds and units, nature of the contacts between beds and units, as well as any fossil material that was present. In cases where a hand lens was insufficient to determine certain characteristics, samples were

7 examined in the lab under a binocular microscope.

Seven detailed sections were measured, drawn, and correlated with the photomosaic. Figure 4 shows where each section is located in the outcrop. Locations for sections were chosen based on the safety and accessibility of the outcrop in various places. The Red Hill outcrop consists of alternating ledges, slopes, and cliff faces that hinder an investigator’s ability to reach portions more than about 8-10 meters above the base. An attempt was made to reach the upper portions using a safety rope and climbing equipment, but this method was deemed unfeasible for covering the span of the outcrop. Thus, sections are limited to the lower (known fossil-bearing) portions of the outcrop. Beds and units between the measured sections were interpolated in Figure 10. Vertical measures were taken in numerous additional locations. This facilitated more accurate placement of non-tabular sand bodies between measured sections.

Fossil distributions in the fossiliferous horizons were determined by fossil counts using a square wooden frame measuring 0.5 m by 0.5m divided with string into four quadrants labeled A, B, C and D respectively, moving clockwise from top left to bottom left. Choosing random locations to sample in an outcrop with limited accessibility proved to be a challenge. Counts were made at each of the measured sections, with further counts being made between sections. Each location is approximately 15 m apart, though this varies based on accessibility. At each location, the frame was placed at two vertical locations within the fossil-bearing zone, one approximately 1 m above the base and the other 0.5 m below the upper contact with the paleosol. Each location was plotted on the cross-section diagram and was described based on its vertical location in the outcrop. The strike of the outcrop was taken at each location in order to determine any patterns of directional bias on the outcropping of fossils. When possible, a count was made from one location in the

8 overlying paleosol. Each count consisted of a tally and description of all fossils measuring more than 2 mm in any dimension. Dip angle, dip direction, and trend were also recorded for these fossils, when applicable. Description of each fossil includes the dimensions of the portion visible in the outcrop, the nature of the fossil material, when possible, as well as the orientation within the bed and the nature and its relationship to other fossils within that bed (i.e. ‘concentration of bone fragments within a cut-and-fill feature 20 cm deep and 1 m wide.’) An approximate count was then taken of all fragments that were smaller than 2 mm in all dimensions. Photos were taken of each location, and were often taken of individual quadrants as well as individual fossil deposits and fossils.

Data

Lithologic Descriptions

In the lower, fossiliferous portion of the outcrop, centimeter-scale changes in lithology were grouped into lithologic facies comprising decimeter- and meter-scale packages, some of which appear to repeat themselves in the less accessible portions of the outcrop just above. Refer to

Figure 4 for section-specific descriptions

Facies A: Facies A consists of brownish red silty very fine sandstone. It exhibits moderate bioturbation, which obscures most bedding. The thickness of the facies varies across the eastern portion of the outcrop at its base. Geometry of the facies is difficult to determine, since its base is generally below ground level and the entire facies dives below ground level to the west. Facies A is a cliff-former. At the base of sections 2, 5, 6, and 7, it grades upwards into a red shale (facies B).

In sections 4, 5, 6, and 7, beds of Facies A are overlain by a sharper contact with a red, bioturbated

9 clay layer (facies C).

Facies B: Facies B consists of lens-shaped packages of red silty clay shale that interfinger with, and pinch out into facies A. It is a slope-former and is often difficult to observe because it is typically covered with colluvium and vegetation. Facies B has a gradational lower contact with the coarser-grained beds of facies A and is overlain by sharp contacts with facies A above. It also seen overlying facies H in sections 2-7.

Facies C: Facies C consists of red, silty clay and exhibits some mottling and green sandstone stringers. It appears to be bioturbated and has none of the shaly parting of facies B. It pinches out to the west, but it is difficult to follow eastward due to colluvium and vegetation cover. It appears to be similar to facies H, though slickensides are not easily recognizable in facies C. This may also be due to the covered state of the beds. Facies C grades upwards into red clay shale (facies D).

Facies D: Facies D consists of red and light green clay shale. It is tabular, eventually pinching out to the east and west. Approximately the top 30 cm of facies D is light green in color. This facies contains some plant material and charcoal from early wildfires (Cressler 1999; 2001). In section 6, facies D grades upwards into green siltstone (facies E). In sections 4 and 5 it is overlain by a sharp contact with a grey sandstone body (facies F).

Facies E: Facies E consists of light to dark green flat-laminated siltstone with some very fine sand.

The siltstone interfingers with beds of sandstone. It contains abundant plant material and charcoal.

It is also the facies in which Hynerpeton was first discovered (refer to Figure 10). Facies E is measured in sections 3 and 6 and is overlain by a gradational contact with a brownish red

10 fossiliferous siltstone (facies G).

Facies F: Facies F consists of resistant cliff-forming beds of very fine sandstone that can be followed varying distances before thinning and pinching out at their margins. Planar cross-bedding is often visible on fresh surfaces. It is mostly planar in form, with several striking exceptions, ranging in thickness from less than 10cm to about 150cm. In the lowest layer of facies F seen at

Red Hill (sections 5 and 7), there is a noticeable portion of positive relief. In the next layer of facies F (near section 1), the basal contact exhibits a significant cut-and-fill feature extending down into facies I below – the largest of its kind seen at the outcrop. Facies F does not appear to be present in again until very near the top of the outcrop. When present, facies F is overlain by a sharp contact with facies G. In places, it also appears laterally to and interfingers with facies G.

Facies G: This facies comprises the major fossil-bearing zone of the Red Hill outcrop. It consists of siltstones with cyclical, thin very fine sandstone beds often forming cut-and-fill features.

Bedding is visible throughout at thicknesses of between two and five centimeters, with planar cross-bedding apparent in a few locations. Bedding is occasionally disturbed by root traces and small burrows (~2cm in diameter). Much of the Red Hill fossil material is found in lag deposits along bedding as well as in small pockets within finer-grained material in facies G.

Facies H: Facies H consists of red, hackly weathered, massive mudstones with slickenside surfaces forming slopes at several levels in the outcrop. It is measured in all seven sections and occurs twice in section 1. Identification of similar slope-forming layers in inaccessible portions of the outcrop is quite easy. Verification of lithology, however, is made difficult by the debris and vegetation cover of these beds. In the lower portions of the outcrop, these layers consist mostly of

11 clay-sized particles with a small amount of silt. Very fine sandstone stringers are often present within muddy portions of facies H. Caliche nodules about one centimeter in diameter are visible throughout the facies. Root traces are common in facies H and appear as tapered vertical forms, often made up of reduced light green silts against the red oxidized sediments. The top of this facies may exhibit some shaly bedding. The upper contact is slightly undulating and is generally overlain be facies B.

Facies proportions

Facies G makes up the largest portion of the measured sections, composing approximately one third of each section. Facies H is the second most abundant facies, composing around 15-20% of each section. Facies B composes 5-10% of each section, with better representation in sections 5 and 7.

Facies A, C, E, and F are not found in every section and each represent about 5-10% of the sections in which they are found.

Sand Body Geometry

The geometries of sand bodies in the Red Hill outcrop are of particular interest in interpreting the nature of the depositional environments. The sandstone beds in the eastern portion of the outcrop are composed of facies F. The flat base of the lowest bed of facies F (Figure 4: sections 5 and 7), when traced across the outcrop, coincides with the base of the vertebrate fossil-bearing zone defined by Woodrow, et al. (1995). These beds are pictured in Figure 5.

At the easternmost end of the exposure, the basal sand body comprises the lower two meters of the fossil-bearing zone. Here, a thin layer of siltstone separates two beds of sandstone. Decimeter- scale planar cross-bedding is visible in a few locations. The body is wedge-shaped, thinning

Figure 4 – Photomosaic of outcrop with seven sections (1-7) in their horizontal locations below. Each section’s base is approximately at road level. 13

Facies Color, etc Texture Form / Geometry Sedimentary Structures Contacts Fossils

A Brownish V.f.l sand Wedge or planar; Moderately bioturbated, Grades into shale in None visible red to silt thickness varies minimal visible bedding places; sharper contact

across lowest with bioturbated clay in portion of outcrop; others cliff-former B Red Silty clay Lens; thins until Shaly Gradational lower None visible disappearing in contacts, sharper upper

facies A contacts C Red Silty clay Wedge or lens; Mottled; very bioturbated, not Gradual upper contact None visible pinches out to west, shaly;

geometry unclear to green stringers of v.f.l. sand to east silt (coloration may to be secondary) D Red; light Clay Lens; thins in both Shaly; ~3dm at top is light Overlain by gray Some plant green directions green (likely secondary) sandstone with sharp material,

contact in places; charcoal elsewhere grades into green siltstone E Light to Silt with Lens; varies locally Alternates between bioturbated Lower contact marked Abundant plant dark some in thickness from siltstone and v.f.l.-v.f.u. by sharp increase in material and

green v.f.l-v.f.u 35cm at max sandstone grain size; overlain by charcoal with some sand thinning until brownish red dark red absent in both fossiliferous siltstone directions F Grey V.f.l. Wedge; thins until Cross-bedding visible in a few Sharp lower and upper None visible sandstone dis-appearing at places; possibly obscured by contacts

various locations; weathering and water-staining locally also on some surfaces outcrops as a large lens as well as a ~1m- thick positive- relief structure G Brownish Silt, some Planar and tabular, Bedding at 2-5cm scale marked Sharp lower contact Small bone beds red v.f.l. sand thickness does not by 2-10mm coarse green vfl with Facies F; fairly and individual

vary greatly over sand at base, overlain by silty, sharp upper contact deposits yield visible extent of less weathered beds, overlain with 8-10 cm of nearly all facies by finer-grained, more transitional shaly animal material weathered beds; many shallow siltstone in places found at the site cut-and-fills carved into including scales, underlying beds; planar X- spines, plates, bedding visible in some beds; bone, teeth, as occasional burrows ~2cm in well as apparent diam. lungfish burrows (Rowe 2006) and some root traces H Dark red Mudstone Hackly weathering distorts any Sharp, undulating upper None visible with some bedding; several intervals of contact

silt light green vfl sandstone; large slickenside surfaces; cm-scale caliche nodules; shaly parting in upper 8cm

Table 1 – Descriptions of facies of fossil-bearing zone

14 gradually to the west until it is completely absent from the section for about 86 meters. At that location on the same horizon, a flat-based convex-up sand body becomes traceable when its thickness is about 5cm. This body thickens steadily to a maximum of about 100cm before thinning again farther to the west. This portion of the sandy body stretches about 16m from east to west, with the middle 5m containing the thickest portion. Once it pinches out to the west, it is not seen again before the horizon dives below road level.

Above these sand bodies lies a fining-upward sequence of sediments, which is in turn overlain by a second localized sand body approximately 80m farther west. This body appears as an obvious cut- and fill feature – one of many in this sediment package, but by far the largest. Measuring approximately 30m across and 1.5-2m deep, it is quite visible up close and from a distance. This feature appears to have carved down through facies B. Figure 6 displays the overall context of sand bodies and cut-and-fill features.

Figure 5 – Flat-based sandstone (facies F) at eastern end of Red Hill outcrop

Results of Fossil Material Survey

Approximately 750 fossils and fossil fragments were counted from 34 locations throughout the study area, covering facies G, H, and I. Refer to Appendix A for fossil sampling locations and total fossil counts at each location. Detailed observations were made on 87 fossils with at least one visible dimension exceeding 2 mm. Refer to Appendix B for data on individual fossils. A survey of the fossil material found within the major known fossil-bearing zone revealed several large-scale patterns and some finer-scale observations. Most obviously, all animal fossil material observed in the survey was found in the lower portions of facies G. Fossil material was observed and tallied in

9 out of 17 sample sites from facies G, with fossil counts ranging from 1 to approximately 400. It should be noted that although fossils were occasionally observed outside of sampling areas in the upper portion of facies G, none fell within the random sampling grids. In contrast to facies G, none of the 12 sample sites from facies H yielded any fossil material. Likewise four samples taken from the overlying facies I (distal splay) and one sample from the upper portion of an overlying bed of facies H yielded no fossil material. Constraints on accessibility to upper portions of the outcrop prevented further investigation into these beds, though these general patterns appeared to hold true at least throughout the lowest five to seven meters of the outcrop.

Discussion

Evidence for Avulsive Processes

The patterns of deposition in the fossiliferous zone of Red Hill are consistent with well known modern avulsion sites such as the Cumberland Marshes in Saskatchewan, Canada (Smith, et al.

1989). Crevasse splays in the Saskatchewan breakout area (Figure 6) have caused most of the regional aggradation that has occurred since the initial levee breach in 1873 (Smith, et al. 1989).

Avulsions can be described in terms of two stages. Stage I begins when flow is diverted from the trunk channel. Depositional packages that form within the avulsion belt during Stage I include progradational crevasse-splay sands, crevasse-splay complex silts, interchannel wetland silts and muds, abandoned channel fills, and channel sands from the constant carving of new minor channels into the other deposits mentioned. Stage I ends and Stage II begins when flow diverts back into the previous trunk channel, or when a new channel begins to handle the entirety of flow. Depositional packages that form within the avulsion belt during Stage II resemble typical floodplain deposits of slowly accumulating clays and possibly organics. Stage II deposition also includes the main channel sands. Several recent studies conclude that an avulsive system cycles through these two systems with a typical period on the order of 1000 years (Smith et al. 1989; Slingerland and Smith

2004).

Stage I deposits consist of sediments deposited by expanding flows and typically exhibit depositional basal contacts with the existing substrate below. Wide and shallow channels are often incised into the splay deposits. Regular reworking of sediment, increased channelization, and coalescing of Stage I splays are common features during this portion of an avulsion. These sedimentary packages accumulate at relatively high rates. At the Red Hill locality, Facies D, E, F, and G are interpreted as Stage I deposits. Stage II deposits consist of overbank floodplain deposition occurring during periods of normal flooding which does not involve diverting the flow of the trunk channel. At the Red Hill locality, paleosols and a few shales (Facies A, B, C, and H) are interpreted as Stage II deposits. (Table 2 gives descriptions and interpretations of each facies.)

Figure 6 depicts a crevasse splay complex prograding downstream before eventually being abandoned. Figure 7 depicts a cross-section of the avulsion belt. The avulsive cycle and its

17 associated sediments consist of everything above the existing floodplain surface (the black bed at the base of the section) up through the next floodplain surface that forms after the channel is stabilized. Avulsion sediments are dominated by fine-grained material – silts, clays, shales -- with flat-based, laterally restricted sandstone bodies as well as cut-and-fill sandstone features that scour out existing beds located proximal to the node of avulsion and at points of high energy flow in the avulsion belt. This model closely matches beds observed at Red Hill. Near the base of the correlated section in Figure 10, there is a series of fine-grained silt and clay beds capped by a paleosol. This bed is interpreted as an ancient floodplain surface. This surface is overlain by shale in the western portion. This shale is interpreted as a shallow floodplain lake, ponded against a previous levee or other topographic high. An aerial view of the Cumberland Marshes shows this to be a common occurrence. Figure 8 shows how such lakes form as flow is redirected from a trunk channel through a crevasse splay, out onto the floodplain. The shales that correspond to this mode of deposition at Red Hill are Facies D, and they contain abundant plant material and charcoal, likely originating on nearby floodplain levees. Facies D is laterally restricted and is not seen farther west.

As the initial crevasse splay progrades out onto the floodplain and down-slope, beds of sandy siltstone and sandstone are deposited. The flat-based, positive-relief sand body (Facies F) in the middle of the correlated section (Figure 10) is interpreted as a crevasse-splay bar deposit. To both the east and west of this feature are scoured channels in-filled with light to dark green sandy siltstone (Facies E). These beds contain abundant plant and material as well as the main articulated vertebrate fossils. At the eastern end of the outcrop, there is a flat-based sandstone wedge that pinches out to the west (see Figure 5 for photo). All of these coarse-grained beds occur in approximately the same horizon. Surrounding them are shaly flood basin deposits (Facies D) and

18 silty, reworked, highly fossiliferous beds (Facies G) containing thin sandstone stringers and abundant cut-and-fill features. This set of facies looks remarkably similar to the cross-section of the Cumberland Marsh (Figure 7). Above this package, a paleosol (Facies H) has formed. This is interpreted as a period during which the avulsion belt has been abandoned and flow has been

Figure 6 – Schematic model of Saskatchewan avulsion belt. (I) shows an avulsive complex prograding downstream during Stage I of an avulsion. (II) shows the avulsion belt during Stage II, after a new trunk channel has stabilized (After Smith et al.1989).

Figure 7 – Cross-section of avulsive cycle sediments after a new trunk channel has formed. Points X and Y refer to Figure 6 (Smith

1989).

19 consolidated in one new channel. The top of this paleosol marks the top of the first major avulsive cycle seen at Red Hill. In Figure 10, this package is marked by two bold lines running through the correlated section. A similar avulsive cycle is seen in Figure 7. Above this package, another shale

(Facies I) is overlain by another flat-based and cut-and-filled sandstone (Facies F). This appears to be the beginning of another avulsive cycle, though only the westernmost section could be measured through its entire thickness.

It appears that these avulsive cycles are repeated two more times immediately above the two measured cycles, but reaching this portion of the outcrop is too dangerous without safety equipment, and was not measured for this study. Figure 11 depicts interpreted Stage I and Stage II deposits up through the outcrop. (Figure 11 is similar to a schematic model presented by

Slingerland and Smith (2004) and depicted in Figure 12.) Facies are inferred at these heights based on apparent grain size and resistance to weathering. If they are indeed avulsive cycles, it appears they are progressively thinner up section, suggesting Red Hill is farther from the node of avulsion during each successive cycle. This can be seen in Figure 11, along with the major features of the lowermost cycles. There is one wedge-shaped cliff-forming sand body visible from road-level near the top of the outcrop, as well as a large multi-storeyed channel body that forms a cliff tens of meters thick in the far western portion of the outcrop. This trunk channel may be the result of one the avulsive cycles, though further investigation would be necessary to make such a claim. Upper portions of the outcrop cannot be accessed without special equipment. It is possible to access these areas using climbing equipment and safety rope harnessed to trees at the apex of the hill, but this method inhibits lateral movement along the outcrop. However, with sufficient time and

Figure 8 – Aerial photo of Saskatchewan breakout area. A breached levee has allowed the crevasse channel to partially divert flow from the trunk channel to the surrounding floodplain. In this case, a lake has ponded against a pre-existing levee (Slingerland and Smith 2004).

assistance, it may be feasible to continue this study on the upper portions of Red Hill.

Simple paleosol packages may be a recognizable trait of avulsive deposits in alluvial deposits.

These packages consist of slightly pedogenically modified fine-grained sediments and essentially unmodified ribbon and sheet sandstone bodies with some cut-and-fill features (Kraus 1996). The mudrocks generally show some evidence of slight pedogenesis including occasional mottling, often associated with root traces, and slickensides typical of the shrinking and swelling of fine-grained sediments exposed to a seasonal wet-dry climate. Individual horizons are rarely identifiable, indicating that soil formation was impeded by high rates of sedimentation (Kraus 1996). Pedogenic slickensides are easily recognizable in the simple paleosols of the Red Hill outcrop. They are visible as smooth, slightly curved surfaces in the clay layers and, and they form many of the angled ledges seen throughout the outcrop. 21

Figure 9 – Aerial photo of Saskatchewan breakout area. The floodplain eventually becomes tiled with ponds and island bordered by stream levees (Slingerland and Smith 2004). .

It is also possible to deduce where on the floodplain various packages of mudrocks were found based on variations in matrix and mottling colors. These variations are typical of modern alluvial soils, and they indicate different degrees of saturation, and thus different topographic settings and distances from trunk channels (Kraus 1996). Further work on the site could attempt to parse out the floodplain using these pedogenic phenomena. This could be of some use if it offered an approximate location for the trunk channel during each avulsion cycle.

Further avulsion studies

There has been much work done on sites of river avulsions in the Holocene, including the

Cumberland Marshes in Saskatchewan, Canada (Smith, et al. 1989; Smith and Perez-Arlucea 1994; 22

Perez-Arlucea and Smith 1999; Morozova and Smith 2003; Slingerland and Smith 2004), the

Rhine-Meuse Delta in the Netherlands (Stouthamer 2001; Makaske and Berendsen 2007), the

Mississippi in the central United States (Aslan et al. 2005), and others. Observations made in these and similar studies have proven invaluable in parsing ancient floodplain sediments now believed to have been deposited during ancient avulsive events, including sites in Pakistan (Willis and

Behrensmeyer 1994; Bridge, et al. 2000), Wyoming (Kraus and Aslan 1993; Kraus and Bown

1993; Davies-Vollum and Wing 1998), Spain (Mohrig, et al. 2000), and elsewhere.

Circumstantial evidence supporting an avulsion model

There are numerous lines of circumstantial evidence supporting an avulsion model for the sedimentary deposits at the base of Red Hill, from the continental and regional framework to specific features seen in the outcrop itself. First, the paleogeographic and tectonic context provides abundant circumstantial evidence, with initial conditions conducive to repeated avulsive events on the alluvial plain. With the subsidence of the Appalachian foreland basin and large volumes of available source sediment being created by the Acadian orogeny to the southeast, a meandering channel delivering sediment to the alluvial plain was likely to become perched above the surrounding topography rather quickly. While it is possible to instigate an avulsive cycle without creating a substantial gradient advantage (Aslan and Autin 2005), floodplain aggradation is a primary factor in bringing about the necessary conditions (Slingerland and Smith 2004). At a certain threshold of slope differential between the existing channel and the drop down to the alluvial plain, a breached channel will nearly always lead to an avulsive system. Studies of modern rivers bear this out, showing that river channels are rarely superelevated to the point where the river bed reaches the average elevation of the floodplain (Mohrig, et al. 2000). On the Catskill delta in the Late Devonian, with subsidence rates estimated at 150-175m/MY (Faill 1985) and an abundant

23 sediment source in the uplifting Acadian mountains, channels likely reached this superelevation threshold with regularity. This would suggest that river avulsions were likely a common occurrence, delivering large volumes of sediment to the floodplain.

Significance for alluvial packages in the geologic record, early tetrapod evolution, and fossil prospecting

To expand our understanding of the paleoenvironments and paleoecology of early tetrapods, it is helpful to be able to predict what types of large-scale depositional packages are most likely to yield significant fossil material. By identifying instances of channel avulsion, and thus instances of rapid deposition in fluvial environments, we can refine our methods of prospecting for fossil deposits.

An avulsive model of deposition holds special significance when applied to paleoenvironments that hosted some of the earliest known tetrapods. Regardless of the impetus for the evolutionary development of robust forelimbs in tetrapods and some ancestral lobe-finned fish, it is rather easy to place such developments in the context of rapidly evolving channels and ephemeral ponds and wetlands that may have been rather commonplace on the Catskill Delta during the Late Devonian.

Figures 8 and 9 provide some insight into the type of landscapes that may have hosted the earliest terrestrial vertebrates.

As for the prospecting of future tetrapod sites, it is useful to realize that such an environment also lends itself to bursts of extremely high sedimentation rates and rapid burial of organic material.

More specifically, a cursory survey of fossil material at the Red Hill locality reveals a strong preservation bias. All fossil material that was found occurs in Stage I deposits, especially in the lower portions of these deposits (Facies D and E and the lower ~1.5m of Facies F.)

Interpretation of Paleoenvironments Facies Description Interpretation Label A Brownish red bioturbated sandy siltstone Proximal well-drained floodplain – sediments deposited on or near alluvial ridge B Lenses of red silty clay shale In-filled abandoned channels and depressions on floodplain C Red bioturbated silty clay with mottling and Floodplain paleosol – sediments deposited farther from green sandstone stringers alluvial ridge; experienced seasonal saturation, causing mottling and reduction of iron in sediments; sand deposited during occasional overbank sheetflow events D Red and light green clay shale containing Poorly drained distal floodplain (pond, wetland) – plant material and charcoal sediments deposited in standing water or high water-table environment; reduction of minerals and preservation of carbon material E Light to dark green siltstone and very fine Swampy wetlands on proximal floodplain – coarser-grained sandstone containing plant material and sediments deposited in standing water; reduction of charcoal minerals and preservation of carbon material F Hard grey very fine lower sandstone Proximal crevasse splay and channel bar– formed in avulsion belt proximal to nodes of avulsion (levee breaches) G Moderate to hard, dark red mudstone with Stage I Avulsion: Proximal crevasse splay complex – some silt; bedding visible on a 2-5cm scale; formed in avulsion belt and consisting of a range of grain burrows ~2cm in diameter sizes delivered by small channels that continuously Several beds of fossil pavement; 2-5cm reworked sediment in the crevasse splay thick; well-indurated; light green coloration common; fragments range 1-5mm with very few up to 60mm; larger fragments are approx. planar and lie flat; smaller fragments are often vertical or at an angle H Soft dark red mudstone with some silt; Stage II Avulsion: Paleosol – formed on floodplain during hackly weathering distorts bedding; long periods of relatively low sedimentation while channel interbeds of light green, very fine sandstone; belt was spatially confined large slickenside surfaces; upper 8cm show shaly parting; slope-former; sharp, slightly undulating upper contact

Table 2 – Interpretation of paleoenvironments

Figure 10 – Seven correlated sections showing lithofacies as well as avulsion interpretation.

Figure 11 – Photomosaic of eastern portion of Red Hill outcrop and drawing of Stage I and Stage II avulsion deposits.

Figure 12 – Schematic model of Stage I and Stage II avulsion deposits. This model is applied to Red Hill in Figure 11 (Slingerland and Smith 2004).

There are two main taphofacies interpreted in Facies G: 1) Basal lags; and, 2) Defecation deposits

(Graham 2009, pers. comm..). Both types of deposits consist of small broken pieces of bone, teeth, scales, plates. Basal lag deposits are found in small cut-and-fill features within the siltstones of

Facies G, and are typically associated with localized sandstone beds. This material has likely been transported and thus is time-averaged and has poor ecological fidelity. Defecation deposits, on the other hand, may represent broken remains of a single individual or a few individuals that lived very near to the site of burial. Further work on these taphofacies may reveal new information on the ecology of the vertebrates at the Red Hill locality.

In addition, the outcrop exhibits channel –margin and standing water taphofacies. The tetrapod

Hynerpeton was found in a channel-margin setting (Facies E between sections 2 and 3), while abundant plant material and occasional arthropods and rhizodontids have been found in standing water deposits (Facies D and E) (Daeschler and Shubin 1994; Rowe 2006, pers. comm..).

Possible limitations of the Red Hill and further work

Stouthamer (2001) indicated in a description of Holocene avulsions in the Netherlands that it was impossible to conclude that an avulsive event was associated with a particular crevasse-splay complex based only on a two-dimensional outcrop. For the purposes of this project, however, merely recognizing a crevasse-splay complex is enough to conclude a mode of deposition that differs significantly from repeated and gradually accumulating overbank deposits. Whether a trunk channel permanently altered its course or ultimately returned to its original channel is not overly relevant to determining a deposition model. This contention by Stouthamer is partly a question of the precise definition of the term “avulsion.” As Slingerland and Smith (2004) noted, the term

“avulsion” has primarily been used to describe a total diversion of a parent, or trunk, channel into a new channel on a floodplain. They suggest, however, that the term is also appropriate in describing short-term and partial flow-switching (Slingerland and Smith 2004). In this sense, an avulsive event has occurred when flow from a trunk channel has been permanently or temporarily diverted out of the channel and onto the adjacent floodplain. Any crevasse-splay involving a significant redirection of flow for some period of time, then, can be considered an avulsive event, even in the absence of direct evidence of a parent channel or a new channel.

It would be possible to strengthen understanding of depositional process and paleoenvironments at

Red Hill in a few ways. Kraus and Gwinn (1997) use geochemical analysis to contrast soil profiles from similar paleosols in the Willwood Formation of Bighorn Basin in Wyoming at different phases of development in order to gauge the depositional environment of each. This would allow a finer parsing of the fining-upward cycles that appear to dominate the lower portion of the outcrop and give a sense of deposition rate and relative position on the floodplain of each cycle on the floodplain. Perhaps more valuable would be a broader study of the Duncannon Member of the

Catskill Delta around Central Pennsylvania. Sites suitable to such expansion of the study area are currently limited in number and scope. But with new construction and maintenance on current road cuts, it may become possible to place the alluvial packages at Red Hill in a broader basinal context by determining how they extend away from the study area. A better three-dimensional view of the packages could also illuminate the source of these sediments and give a sense of overall flow directions of the minor channels evidenced by the small cut-and-fill features ubiquitous in the Stage

I avulsion sediments. With a clearer picture of the flow depth and superelevation of the channels delivering sediment to the Red Hill site, the initial conditions would become clearer. This would provide a more complete picture of the typical cycle of channel aggradation followed by levee breach and crevasse-splay deposition.

Conclusion

The Red Hill site has proven to be an extremely valuable source of Late Devonian vertebrate fossil material and has provided us with numerous insights into early lineages of tetrapods and their ancestors, the lobe-finned fish. By parsing out the facies in which this material is most often found, we can produce an even more detailed picture of where these lineages evolved and why they are so well preserved at this site. The fossil-bearing zone, made up of facies D, E, F, and G (as well as the non-fossiliferous facies H), is interpreted as a Stage I avulsion package. Facies D is a shale that formed in a laterally-restricted pond on the ancient floodplain as flow was diverted from the parent channel. Facies E and F were deposited as the crevasse splay prograded onto the floodplain.

Facies G formed as small shallow channels migrated across the avulsion belt, reworking the sediments until most of the diverted flow stabilized in a new channel or channels and a paleosol developed, capping the package. The avulsive model of deposition presented here is supported by

30 the stratigraphy and sedimentology of the site as well as by fossil occurrence data, and it appears to be the most appropriate model to describe the paleoenvironments found at the Red Hill outcrop.

In future studies of similar sedimentary packages, the avulsive model may be able to provide researchers with clues as to likely facies in which to begin searching for tetrapod material as well as associated fossil material. This could certainly be of use on the Catskill Delta, where one would expect to find similar events of avulsion and rapid deposition along the numerous channel systems that carried sediment out of the newly formed Acadian Mountains into the Appalachian Basin. But it may also prove applicable to sites as yet unassociated with avulsive deposition or early tetrapod environments.

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Appendix A – Fossil sampling location data Approx. horiz. Approx. horiz. pos. (m) Facies Top/Bottom Outcrop Strike (deg E of N) (#) >1mmFossils (#) >2mmFossils Fossils (~total #) Photos (#) Date 25 B Top 105 0 0 0 2 11/26/2008 29 H Bottom 120 0 0 0 1 11/26/2008 31 G Bottom 105 21 16 170 7 11/26/2008 33 G Bottom 76 4 2 9 7 11/26/2008 38 G Bottom 120 0 0 0 5 11/26/2008 40 G Top 125 0 0 0 6 11/26/2008 58 G Bottom 125 14 2 60 6 11/26/2008 61 G Top 140 0 0 0 1 11/26/2008 61 G Bottom 140 0 0 0 1 11/26/2008 83 G Top 136 0 0 0 3 12/8/2008 86 G Bottom 210 0 0 0 5 12/8/2008 88 G Bottom 109 4 4 4 5 12/8/2008 100 G Bottom 135 0 0 0 1 12/8/2008 100 G Top 117 0 0 0 1 12/8/2008 102 G Bottom 178 0 0 0 1 12/8/2008 117 G Bottom 107 38 26 400 10 12/8/2008 117 G Top 108 0 0 0 1 12/8/2008 132 G Bottom 104 0 0 0 1 12/8/2008 138 G Bottom 141 0 0 0 1 12/8/2008 144 G Bottom 125 0 0 0 5 12/8/2008 144 G Top 129 0 0 0 5 12/8/2008 157 G Bottom 104 1 1 1 1 12/14/2008 157 G Top 115 0 0 0 4 12/14/2008 157 G Top 135 0 0 0 1 12/14/2008 171 G Bottom 96 11 11 50 7 12/14/2008 171 G Top 100 0 0 0 1 12/14/2008 173 G Bottom 128 11 11 60 6 12/14/2008 173 G Top 132 0 0 0 4 12/14/2008 173 G Top 124 0 0 0 5 12/14/2008 186 G Bottom 102 1 1 8 1 12/14/2008 186 G Top 110 0 0 0 1 12/14/2008 204 G Bottom 120 0 0 0 1 12/14/2008 204 G Top 128 0 0 0 1 12/14/2008 223 G Top 130 0 0 0 5 12/14/2008

Appendix B – Individual fossil data Fossil ID# Fossil Location (I-#) Approx. horiz. (m) Facies Upper / Lower Outcrop Strike (deg E of N) Quadrant Type Fossil (cm) Vis. Length (cm) Vis. Width (cm^2) area X-section ~Dip dir (deg E of N) Dip (deg) Trend (deg E of N) Notes C-F 20cm deep, ~2m wide; red hackly 1 16 31 G Lower 79 A Scale 1 0.1 0.1 215 45 - siltstone 2 16 31 G Lower 79 A Scale 1 0.1 0.1 75 75 - " 3 16 31 G Lower 79 A Scale 0.5 0.1 0.05 - 0 - " 4 16 31 G Lower 79 A Scale 0.5 0.1 0.05 112 45 - " 5 16 31 G Lower 79 B Spine 1 0.5 0.5 - 0 94 " 6 16 31 G Lower 79 B Bone 3 1.5 4.5 - 0 159 " 7 16 31 G Lower 79 B Scale 1 0.2 0.2 135 20 - " 8 16 31 G Lower 79 B Scale 1 0.2 0.2 - 0 - " 9 16 31 G Lower 79 B Scale 0.8 0.2 0.16 195 15 - " 10 16 31 G Lower 79 B Scale 0.8 0.1 0.08 - 0 - " 11 16 31 G Lower 79 B Scale 0.5 0.1 0.05 - 0 - " 12 16 31 G Lower 79 B Frag? 0.3 0.1 0.03 - 0 - " 13 16 31 G Lower 79 B Frag? 0.3 0.1 0.03 - 0 - " 14 16 31 G Lower 79 B Frag? 0.2 0.2 0.04 - 0 - " 15 16 31 G Lower 79 B Frag? 0.2 0.1 0.02 - 0 - " 16 16 31 G Lower 79 C Frag? 0.2 0.1 0.02 - 0 - Not in C-F; fairly massive siltstone Continuous bed w/ scattered fossils; 17 17 33 G Lower 50 A Plate 2 0.5 1 - 0 - hackly red siltstone 18 17 33 G Lower 50 A Plate 1 1 1 - 0 - " 19 17 33 G Lower 50 B Bone? 2 2 4 - 0 29 " Across several thin beds; massive red 20 17 33 G Lower 50 C Spine 1.5 0.5 0.75 - 0 49 siltstone 21 17 33 G Lower 50 D Plate 1 0.5 0.5 - 0 - " 22 17 33 G Lower 50 D Plate 0.5 0.5 0.25 - 0 - " 23 17 33 G Lower 50 D Plate 0.5 0.5 0.25 - 0 - "

24 30 58 G Lower 99 A Plate 2 0.1 0.2 - 0 - No C-F; ~4cm thick massize siltstone bed 25 30 58 G Lower 99 A Plate 1 0.1 0.1 - 0 - " 26 30 58 G Lower 99 A Frag? 0.3 0.1 0.03 - 0 - " 27 30 58 G Lower 99 A Frag? 0.2 0.2 0.04 - 0 - " 28 30 58 G Lower 99 A Frag? 0.2 0.2 0.04 - 0 - " 29 30 58 G Lower 99 A Frag? 0.2 0.1 0.02 - 0 - " 30 30 58 G Lower 99 B Scale 2 0.1 0.2 235 60 - " 31 30 58 G Lower 99 B Scale 1 0.1 0.1 - 0 - " 32 30 58 G Lower 99 B Frag? 0.2 0.2 0.04 - 0 - " 33 30 58 G Lower 99 B Frag? 0.2 0.2 0.04 - 0 - " 34 30 58 G Lower 99 B Frag? 0.2 0.1 0.02 - 0 - " 35 30 58 G Lower 99 B Frag? 0.2 0.1 0.02 - 0 - " 36 30 58 G Lower 99 C Frag? 0.3 0.1 0.03 - 0 - Hackly red siltstone lens 37 30 58 G Lower 99 C Frag? 0.2 0.1 0.02 - 0 - " 38 46 88 G Lower 83 A Frag? 0.5 0.5 0.25 - 0 - 39 46 88 G Lower 83 A Frag? 0.2 0.1 0.02 - 0 - Single bedding surface; red massive 40 46 88 G Lower 83 D Bone? 4 1 4 - 0 - siltstone 41 46 88 G Lower 83 D Tooth 0.7 0.1 0.07 - 0 72 "

Appendix B (con’t) -- Individual fossil data Fossil ID# Fossil Location (I-#) Approx. horiz. (m) Facies Upper / Lower Outcrop Strike (deg E of N) Quadrant Type Fossil Visible Length (cm) (cm) Width Visible area (cm^2)X-section ~Dip dir (deg E of N) Dip (deg) Trend (deg E of N) Notes One continuous bed; silt to vfl sand; 42 61 117 G Lower 81 A Plate 3.5 0.2 0.7 - 0 - very fossiliferous 43 61 117 G Lower 81 A Plate 0.6 0.1 0.06 95 60 - " 44 61 117 G Lower 81 A Frag? 0.2 0.1 0.02 - 0 - " Single bedding surface; red massive 45 61 117 G Lower 81 B Plate 3 0.2 0.6 - 0 - siltstone 46 61 117 G Lower 81 B Plate 1.6 0.2 0.32 - 0 - " Small fragments in three beds; red 47 61 117 G Lower 81 B Frag? 0.4 0.1 0.04 - 0 - massive silt to vfl sand 48 61 117 G Lower 81 B Frag? 0.2 0.1 0.02 - 0 - " 49 61 117 G Lower 81 B Frag? 0.2 0.1 0.02 - 0 - Minor" fossil bed above major one; 50 61 117 G Lower 81 C Scale 0.7 0.1 0.07 - 0 - massive red siltstone; ~.75m long 51 61 117 G Lower 81 C Plate 0.5 0.3 0.15 - 0 - "

Major (high-concentration) lag deposit; massive silt to vfl sand; ~200 52 61 117 G Lower 81 C Scale 0.8 0.1 0.08 - 0 - fossils in sample area; ~1.5m long 53 61 117 G Lower 81 C Scale 0.4 0.1 0.04 - 0 - " 54 61 117 G Lower 81 C Scale 0.6 0.1 0.06 - 0 - " 55 61 117 G Lower 81 C Scale 0.7 0.1 0.07 - 0 - " 56 61 117 G Lower 81 C Scale 0.5 0.5 0.25 - 0 - " Minor fossil bed above major one; 57 61 117 G Lower 81 D Scale 0.4 0.1 0.04 - 0 - massive red siltstone; ~.75m long 58 61 117 G Lower 81 D Frag? 0.3 0.1 0.03 - 0 - " 59 61 117 G Lower 81 D Frag? 0.3 0.3 0.09 - 0 - "

60 61 117 G Lower 81 D Plate 0.8 0.5 0.4 184 10 - "

Major (high-concentration) lag deposit; massive silt to vfl sand; ~200 61 61 117 G Lower 81 D Scale 0.8 0.1 0.08 - 0 - fossils in sample area; ~1.5m long 62 61 117 G Lower 81 D Plate 0.5 0.3 0.15 - 0 - " 63 61 117 G Lower 81 D Frag? 0.2 0.2 0.04 - 0 - " 64 61 117 G Lower 81 D Frag? 0.2 0.1 0.02 - 0 - " 65 61 117 G Lower 81 D Frag? 0.2 0.1 0.02 - 0 - "

66 82 157 G Lower 78 A Scale 4 0.1 0.4 - 0 - Fossil-poor zone; red hackly siltstone Four lightly concentrated layers within ~10cm vert.; hackly red 67 89 171 G Lower 70 A Scale 0.35 0.1 0.035 274 10 - siltstone 68 89 171 G Lower 70 A Frag? 0.3 0.1 0.03 - 0 - "

69 89 171 G Lower 70 A Scale 1 0.1 0.1 - 0 - " 70 89 171 G Lower 70 A Plate 2.5 0.3 0.75 - 0 - " 71 89 171 G Lower 70 B Plate 1 0.3 0.3 - 0 - "

Appendix B (con’t) -- Individual fossil data Fossil ID# Fossil Location (I-#) Approx. horiz. (m) Facies Upper / Lower Outcrop Strike (deg E of N) Quadrant Type Fossil (cm) Vis. Length (cm) Vis. Width (cm^2) area X-section ~Dip dir (deg E of N) Dip (deg) Trend (deg E of N) Notes 72 89 171 G Lower 70 B Scale 0.6 0.1 0.06 108 10 - " 73 89 171 G Lower 70 B Scale 1.5 0.1 0.15 - 0 - " 74 89 171 G Lower 70 B Plate 2.5 0.4 1 104 20 - " 75 89 171 G Lower 70 B Plate 1 0.3 0.3 114 20 - " 76 89 171 G Lower 70 B Bone? 2 0.4 0.8 - 0 - " 77 89 171 G Lower 70 B Plate 2.8 0.2 0.56 - 0 - " Lightly concentrated bed 20cm thick; 78 90 173 G Lower 102 A Scale 4 0.1 0.4 116 15 - thinly bedded (1-2mm) siltstone 79 90 173 G Lower 102 A Scale 3 0.1 0.3 110 15 - " 80 90 173 G Lower 102 A Frag? 0.4 0.2 0.08 - 0 - " 81 90 173 G Lower 102 A Plate 1 0.3 0.3 - 0 - " 82 90 173 G Lower 102 A Scale 0.5 0.1 0.05 - 0 - " 83 90 173 G Lower 102 A Scale 0.4 0.1 0.04 - 0 - " 84 90 173 G Lower 102 A Scale 1 0.2 0.2 4 10 - " 85 90 173 G Lower 102 B Scale 1 0.1 0.1 - 0 - " 86 90 173 G Lower 102 B Scale 1.5 0.1 0.15 - 0 - " 87 90 173 G Lower 102 B Frag? 0.4 0.1 0.04 - 0 - " 88 90 173 G Lower 102 B Scale 0.8 0.1 0.08 - 0 - " ~10 fossils in 2cm-thick laminated 89 97 186 G Lower 76 A Frag? 0.4 0.2 0.08 - 0 - bedset; silty shale