A Thesis

entitled

The Chronology of Glacial Near Mongo, – Evidence for the Early

Retreat of the Saginaw Lobe

by

Thomas R. Valachovics

Submitted to the Graduate Faculty as partial fulfillment of the requirements for the

Master of Science Degree in

Geology

______Timothy G. Fisher, PhD., Committee Chair

______James M. Martin-Hayden, PhD., Committee Member

______Jose Luis Antinao-Rojas, PhD., Committee Member

______Cyndee Gruden, PhD, Dean College of Graduate Studies

The University of Toledo

August 2019

Copyright 2019 Thomas R. Valachovics

This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of

The Chronology of Glacial Landforms Near Mongo, Indiana – Evidence for the Early Retreat of the Saginaw Lobe by

Thomas R. Valachovics

Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in

The University of Toledo August 2019

The Saginaw Lobe of the Laurentide occupied central and during the . Evidence exists that the Saginaw

Lobe retreated earlier than its neighboring lobes but attempts to constrain this retreat using radiocarbon dating methods has led to conflicting results. Optically stimulated luminescence dating (OSL) offers an alternative methodology to date deglacial deposits.

The Pigeon River Meltwater (PRMC) was formed by a large, erosional pulse of meltwater that exited the ice sheet and eroded through the deglaciated landscape previously occupied by the Saginaw Lobe. that partially fill the PRMC were dated using OSL. Minimum ages for the retreat of the Saginaw Lobe were acquired to test the hypothesis that the Mongo area is ice free by 23 ka.

A better understanding of of study area was gained through mapping of surficial landforms. Knowledge of the subsurface stratigraphy was gained through geoprobe coring, vibracoring, and ground penetrating radar (GPR). Tunnel channels that are crosscut by the PRMC and the Sturgis were found to be ice collapse features that formed when buried ice deposited within the tunnel channels melted out after being covered by younger deposits.

iii Optically stimulated luminescence dating is used to determine when outwash was

deposited within the PRMC. Four OSL ages record deposition in the PRMC following retreat of the Saginaw Lobe: 15.7 ± 2.7 ka, 17.1 ± 3.0 ka, 23.3 ± 5.8 ka, and

23.4 ± 4.4 ka. OSL ages therefore suggest that meltwater flowed through the PRMC as early as 23.3 ± 5.8 ka. The maximum PRMC age of 23.3 ± 5.8 ka is used as a minimum age for the final retreat of the Saginaw Lobe from Indiana. Three former Huron-Erie

Lobe ice margins were mapped in the study area and further constrain ice sheet retreat.

The Huron-Erie Lobe acted as the source of meltwater and sediment in the PRMC.

Additionally, OSL ages of: 10.9 ± 0.9 ka, and 12.5 ± 1.5 ka from the Mongo and one OSL age of 10.6 ± 0.8 ka from the top of the outwash surface buried by dunes record eolian activity during the .

iv

Acknowledgements

I would like to begin by thanking my advisor Dr. Timothy Fisher for his guidance throughout this project from helping formulate a research question to editing my Thesis.

I would also like to especially thank Dr. Jose Luis Antinao-Rojas and Dr. Henry Loope from the IGWS, who provided seemingly endless support including taking me on field trips, mobilizing the geoprobe, teaching me the methods and analysis for OSL, and loaning time on their OSL machine for my samples. I could not have done any of this without their support and the support of the IGWS. Additionally, I would like to thank

Dr. Jose Luis Antinao-Rojas and Dr. Jamie Martin-Hayden for serving on my committee.

Next, I would like to thank everyone who helped me collect field data: Drew

Packman and Don Tripp from the IGWS; Alex Sodeman, Dustin Dehm, Brian Samsen, and Sarah McGuinness from the University of Toledo. Their time spent in the field was invaluable. I would like to thank Brittany Slate and Marissa Schorr from the IGWS for their assistance prepping OSL samples. Additionally, I would also like to thank Savanah

Vaughn the manager of the Pigeon River Fish and Wildlife Area for allowing access to the PRFWA property and working with hunters to allow for safe and efficient field work.

I would also like to thank Steven Murphy the machinist at the University of Toledo.

Funding was provided by the University of Toledo GSA Graduate Research

Award and the University of Toledo Department of .

v

Table of Contents

Abstract ...... iii

Acknowledgements ...... v

Table of Contents ...... vi

List of Tables ...... ix

List of Figures ...... x

1 Introduction ...... 1

1.1 Introduction ...... 1

1.2 Study Area ...... 3

1.3 Background ...... 6

1.4 Deglacial Chronology of the Huron-Erie Lobe and Michigan Lobe ...... 7

1.5 Saginaw Lobe...... 13

1.6 Hypothesis for Tunnel Channel Formation...... 18

1.6.1 Incipient Tunnel Channel Model ...... 19

1.6.2 Palimpsest Tunnel Channel Hypothesis...... 20

1.7 Objective and Hypothesis ...... 22

2 Methods ...... 23

2.1 Introduction ...... 23

2.2 Maps and Digital Elevation Model ...... 23

vi 2.3 Field Work ...... 24

2.4 Ground Penetrating Radar...... 25

2.5 Radiocarbon Dating ...... 26

2.6 Optically Stimulated Luminescence ...... 27

3 Results…………...... 30

3.1 Introduction ...... 30

3.2 Surficial Geology ...... 30

3.2.1 Pigeon River ...... 32

3.2.2 Huron-Erie Lobe Fans ...... 35

3.2.3 Sturgis Moraine and Fans ...... 37

3.2.4 Tunnel Channels ...... 39

3.2.5 ...... 44

3.2.6 Ice-Walled Lake Plains ...... 48

3.2.7 Mongo Dunes ...... 48

3.2.8 Relationships ...... 49

3.3 Sediment Cores ...... 51

3.4 Ground Penetrating Radar (GPR) ...... 57

3.5 Stratigraphy ...... 64

3.6 Radiocarbon Ages ...... 68

3.7 Optically Stimulated Luminesce ...... 68

4 Discussion and Conclusions ...... 74

4.1 Introduction ...... 74

4.2 Stratigarphy ...... 74

vii 4.3 Geochronology ...... 77

4.4 Deglaciation ...... 78

4.5 Northern Indiana OSL ...... 85

4.6 Conclusions ...... 86

4.7 Implications ...... 87

4.8 Future Work ...... 88

References ...... 89

A Ground Penetrating Radar ...... 97

B Optically Stimulated Luminescence ...... 106

viii

List of Tables

1.1 Approx. ages and events associated with the , Saginaw, and

Huron-Erie Lobes...... 9

3.1 Sediment cores ...... 52

3.2 Radiocarbon results ...... 68

3.3 OSL sample locations ...... 69

3.4 Dosimetrically significant elements ...... 69

3.5 OSL results...... 69

4.1 Rejected aliquots ...... 85

B.1 Measured dosimetrically significant elements ...... 106

B.2 IGWS-48 aliquots ...... 107

B.3 IGWS-58 aliquots ...... 108

B.4 IGWS-59 aliquots ...... 109

B.5 IGWS-60 aliquots ...... 111

B.6 IGWS-61 aliquots ...... 113

B.7 IGWS-149 aliquots ...... 114

B.8 IGWS-150 aliquots ...... 115

B.9 IGWS-153 aliquots ...... 117

ix

List of Figures

1 – 1 Thesis Study Area ...... 2

1 – 2 Surficial Geology of La Grange, Stroh, and Orland area as mapped by others ...... 4

1 – 3 Stratigraphy of the area around the Sturgis and Shipshewana ...... 6

1 – 4 Late Wisconsinan regional setting ...... 8

1 – 5 Major moraines in the Great region ...... 11

1 – 6 Union City Moraine position and 18.2 ka isochrone ...... 12

1 – 7 Map of Wisconsinan age moraines from Zumberge (1960) ...... 15

1 – 8 Deglacial isochrones of moraines based on radiocarbon ages ...... 17

1 – 9 Development of incipient tunnel channels from Sjogren et al. (2012) ...... 21

1 – 10 Development of palimpsest tunnel channels from Clayton et al. (1999) ...... 21

2 – 1 Pigeon River Fish and Wildlife Area ...... 25

2 – 2 OSL sample collection from core ...... 28

3 – 1 Surfical geology map ...... 32

3 – 2 PRMC where it merges with the Lima Plain ...... 33

3 – 3 Shift from subglacial channel to subaerial channel for the PRMC ...... 33

3 – 4 Crosscutting relationship between tunnel channels and Brighton Fan ...... 36

3 – 5 Sturgis Moraine fans ...... 38

3 – 6 Bend in Sturgis Moraine ...... 38

x 3 – 7 Sinuous tunnel channels ...... 41

3 – 8 Tunnel channel impression through the Brighton Fan ...... 42

3 – 9 Two-Track morphology tunnel channels ...... 43

3 – 10 Pitted tunnel channel morphology ...... 43

3 – 11 Eskers found within tunnel channels ...... 46

3 – 12 Borrow pit outcrop ...... 47

3 – 13 Sediment cores map ...... 52

3 – 14 Core logs of sediment cores ...... 53-54

3 – 15 GPR transects ...... 57

3 – 16 GPR transect PR-02 ...... 59

3 – 17 GPR transect PR-04 ...... 60

3 – 18 GPR transect PR-08 ...... 61

3 – 19 GPR transect PR-09 ...... 63

3 – 20 Schematic of near surface stratigraphy sampled by geoprobe ...... 65

3 – 21 Cross section across the PRMC ...... 65

3 – 22 Cross section across the Otter Lake Tunnel Channel ...... 66

3 – 23 Cross section along the PRMC ...... 67

3 – 24 Radial plot of IGWS 59 ...... 71

3 – 25 OSL age distribution ...... 72

4 – 1 Conceptual stratigraphic cross section ...... 75

4 – 2 Formation of tunnel channels ...... 76

4 – 3 Deglacial ages between the Shipshewana and Sturgis Moraine ...... 78

4 – 4 Saginaw Lobe tunnel channels ...... 80

xi 4 – 5 Deposition of ...... 81

4 – 6 Ice position during deposition of the Brighton Fan ...... 81

4 – 7 Ice position during formation of the Sturgis Moraine ...... 82

4 – 8 Ice position during formation of the Flint Fan and PRMC ...... 83

4 – 9 Final form of landforms used to reconstruct deglaciation ...... 84

A – 1 Common midpoint survey of the PRMC ...... 97

A – 2 GPR transect PR-01 ...... 98

A – 3 GPR transect PR-03 ...... 99

A – 4 GPR transect PR-05 ...... 100

A – 5 GPR transect PR-10 ...... 101

A – 6 GPR transect PR-11 ...... 102

A – 7 GPR transect PR-12 ...... 103

A – 8 GPR transect PR-18 ...... 104

A – 9 GPR transect PR-19 ...... 105

B – 1 Radial plot for IGWS-48 ...... 107

B – 2 Radial plot for IGWS-58 ...... 108

B – 3 Radial plot for IGWS-59 ...... 110

B – 4 Radial plot for IGWS-60 ...... 112

B – 5 Radial plot for IGWS-61 ...... 113

B – 6 Radial plot for IGWS-149 ...... 114

B – 7 Radial plot for IGWS-150 ...... 116

B – 8 Radial plot for IGWS-153 ...... 118

xii Chapter 1

Introduction

1.1 Introduction

An analog for understanding modern retreat of continental ice sheets is to study the events that occurred at the end of the Wisconsinan Glaciation. The final retreat of the

Laurentide Ice Sheet (LIS) in northern Indiana left a palimpsest landscape of subglacial and ice-marginal landforms from multiple glacial advances and subsequent retreats.

The complicated landscape of northern Indiana is from the Saginaw Lobe being out of phase with its neighboring Huron-Erie and Lake Michigan Lobes (Leverett and

Taylor, 1915). Previous attempts to provide chronology for the retreat of the Saginaw

Lobe relies heavily on the correlation of moraines (Fullerton, 1980). Attempts to use geochronology to puzzle out the retreat of the Saginaw lobe has been further complicated by an age disparity between younger radiocarbon chronology and the older OSL ages

(Dzeikan, 2017).

The study area (Figure 1-1) in northern Indiana is complicated by the merging and overlapping of both the Saginaw Lobe and Huron-Erie Lobe in an interlobate position. In

1

the interlobate area of northern Indiana glacial landforms formed as a result of the two different ice orientations.

Determining the age of deglacial features in the interlobate area will help to understand the timing of the retreat of the Saginaw Lobe and the Huron-Erie Lobe, which may contribute to a more complete understanding of modern and future ice sheet behavior.

Figure 1-1: Thesis Study Area (A) box shows location of map B (B) box shows location of map C. (C) LiDAR derived DEM and hillshade of study area. Lighter greys are higher elevations and dark grays are lower topographically. The Pigeon River Meltwater Channel (PRMC) is the sinuous, dark grey that trends east-west.

2

1.2 Study Area

A brief introduction to the study area is presented here to give an overview of the

glacial and proglacial landforms within the study area. A more detailed description and

background of the specific landforms are included in Chapter 3 which includes both the interpretations of previous workers as well as geomorphic observations.

The retreat of the ice sheet left a palimpsest landscape of subglacial and ice-

marginal landforms from multiple glacial events. A palimpsest landscape is when a

paleo-landscape has been overprinted by later processes, but traces of the original

landscape are still visible. Northeastern Indiana near the town of Mongo (Figure 1-1) is

the location of one such palimpsest landscape. Located at the margin of the Saginaw

Lobe and the Huron-Erie Lobe; the landforms are a result of the advances and retreats of

these two ice lobes and other post glacial processes that occurred after ice retreat. The

Wisconsinan aged deposits are mapped as: undifferentiated outwash of the Atherton

Formation, Huron-Erie Lobe sourced silty clay-loam of the Lagro Formation, and the

loam till of the Trafalgar Formation (Gray, 1989). The landforms and near-surface

sediment of the study area was mapped at the 7.5-minute scale by Brown et al. (1998)

and Brown and Jones (1999a, 1999b) (Figure 1-2). The most pronounced feature of the

study area is the large valley that the Pigeon River occupies. The Pigeon River

Meltwater Channel (PRMC) has been interpreted as a Huron-Erie Lobe meltwater

pathway that drained water to the west (Zumberge, 1960).

The PRMC has a crosscutting relationship with two sets of tunnel channels.

Tunnel channels are elongated channelized, subglacial drainage ways formed by high

velocity meltwater flows (Piotrowski, 1994). Similar to tunnel channels north of the

3

Figure 1-2a: Surficial Geology of LaGrange County, Indiana as mapped by Fleming et al. (1997) and Brown et al. (1998); digitized by Karaffa et al. (2010). The study area is boxed area including portions of the Lima Plain, Brighton Fan, and Interlobate Terrain. Gray area to east is mapped in Figure 1-2b.

Figure 1-2b: Surficial geology of Stroh and Orland 7.5 minute quads as mapped by Brown and Jones (1999a, 1999b); digitized by the Indiana Geological and Water Survey. Study area is boxed area. Gray area to east is mapped in Figure 1-2a.

4

Sturgis Moraine (Fisher et al., 2005); the tunnel channels near the PRMC have two

orientations. North of the PRMC is the Brighton . The southern edge of this

fan is cut by the PRMC. South of the PRMC is the Topeka Fan; an outwash fan covered

by a thin till (Brown et al., 1998). Occupying the inner part of the valley is a field

that likely began to form after ice retreat approximately 16 - 17 ka (Horton, 2015). The

dunes were then reactivated at 14.1 ka and those in the uplands were reactivated at 12.2

ka (Fisher et al., 2019). At the northern edge of the study area is the Sturgis Moraine

(Figure 1-2a). A product of the Saginaw Lobe the Sturgis Moraine has a well-developed

ridge and has been interpreted to have formed during the recession of the Saginaw Lobe

(Leverett and Taylor, 1915). The eastern edge of the Sturgis Moraine has not been

mapped in as much detail.

The southern edge of the study area is a complicated landscape mapped by Brown

et al., (1998) as interlobate terrain. The interlobate terrain is a high relief meltwater

scoured landscape (Brown et al., 1998).

A general stratigraphy of the area between the Shipshewana Moraine and the

Sturgis Moraine was is interpreted by Fleming et al., (1997) (Figure 1-3). However, this

stratigraphy does not differentiate between deposits of the Huron-Erie Lobe or the

Saginaw Lobe. Stratigraphic interpretations by Fleming et al., (1997) and Brown et al.,

(1998) are too coarse to attempt to explain the tunnel channels through the PRMC or determine a sequence of deglacial deposits.

This study will help to shed some light onto the formation of this landscape by using newly developed techniques such as Light Detection and Ranging (LiDAR) and

5

Optically Stimulated Luminescence (OSL) to provide a more detailed map and

chronology.

Figure 1-3: Stratigraphy of the area around the Sturgis and Shipshewana Moraines from Fleming et al. (1997) with modifications from Dzeikan (2017)

1.3 Background

The surficial geology of the upper Midwest of the United States is defined by the

Late Glaciation the most recent of which, the Late Wisconsinan, saw ice extend

from Canada into the United States (Colgan et al., 2003). After reaching its maximum extent and stagnating near that position for several thousand the LIS began its retreat northward (Larson and Schaetzl, 2001). The retreat of the ice sheet was periodically interrupted by several major re-advances.

6

Ice flow in the region was defined by large lobes splaying out into the lowlands of Indiana, Michigan, and (Larson and Schaetzl, 2001). Northern

Indiana was modified by three glacial lobes (Figure 1-4). To the west was the Lake

Michigan Lobe which flowed down the modern day Lake Michigan basin to nearly 38º N

(Leverett and Taylor, 1915; Colgan et al., 2003). To the east the Huron-Erie Lobe advanced out of the Huron and Erie lowlands and into Michigan and Indiana and at its furthest extended to 39º N (Leverett and Taylor, 1915; Colgan et al., 2003). Competing for space between these two lobes is the Saginaw Lobe which advanced through the

Saginaw (Leverett and Taylor, 1915; Dworkin et al., 1985).

1.4 Deglacial Chronology of the Huron-Erie Lobe and Lake Michigan Lobe

The Saginaw Lobe has been interpreted to have been out of phase with the Huron-

Erie Lobe and Lake Michigan Lobe, with much of its chronologic constraints based on geomorphic relationships with the neighboring lobes. To understand the retreat of the

Saginaw lobe an understanding of the chronology of the Huron-Erie Lobe and Lake

Michigan Lobe is necessary (Table 1.1). During the time period relevant to this study the

Huron-Erie Lobe and Lake Michigan Lobe appear to be in phase with synchronous advances and retreats. The LIS reached its maximum extent in the at the Hartwell Moraine (Figure 1-4) in southern Ohio. From 23 to 19.8 ka cal. yr BP the ice sheet receded slowly northward (Mickelson et al., 1983; Larson and Schaetzl, 2001;

Howard, 2010). The next 1,500 years is marked by rapid retreat of the ice back to the

7

Figure 1-4: Late Wisconsinan regional setting showing position of ice. Red boxshows study area. Black arrows show ice flow direction. Ice lobe boundaries based on till associations from Gray (1989) and mapping in the Atlas of the United States (Richmond and Fullerton, 1983; Richmond and Fullerton, 1984; and Fullerton and Richmond, 1991).

8

Erie Lobe. aw Lobe, and aw Huron - in

Modified from Howardal. from Fisher (2015). Modified and (2010)et ents associated with the Lake Michigan Lobe, Sag Lobe, Michigan Lake the with Table 1.1:agesents associated Approximate and ev

9

Lake Michigan, Huron, and Erie basins, known as the Erie Interstade. The major event

of the Erie Interstade is the , a major meltwater pulse, originating near

the Kalamazoo Moraine and cutting through the Sturgis Moraine and Shipshewana

Moraine before flowing across Indiana and . (Figure 1-5) (Mickelson et al., 1983;

Curry et al., 2014).

The Port Bruce Stade follows the Erie Interstade and is a period of glacial advance to the Union City Moraine and (Figure 1-6). The maximum

Union City Moraine age is constrained by spruce wood dated at 14,780 ± 192 14C yrs BP

(~18.2 ka cal yrs BP) (Ogden and Hay, 1973). The Lake Michigan Lobe re-advanced to

the Valparaiso Moraine (Fullerton, 1980; Mickelson et al., 1983) and possibly over the

Valparaiso Moraine where there are three small fields (Kehew et al., 2005).

Organics in the Valparaiso Moraine have been dated at 18.1 ka cal yrs BP (Curry et al.,

2018). The retreat during the Port Bruce Stade is also responsible for a number of Huron-

Erie Lobe moraines between the Union City and Defiance Moraines (Figure 1-5).

The Mackinaw Interstade followed the Port Bruce Stade. The Michigan Lobe retreated far enough northward to allow eastward drainage through the Mackinaw .

Originally the age was constrained by the Cheboygan bryophyte bed, however, redating of the site has revised the age (Larson et al., 1994).

The end of the Mackinaw Interstade is marked by a readvance called the Port

Huron Stade. Ice readvanced into Michigan and formed the Port Huron Moraine. The

Western basin remained deglaciated during the Port Huron Stade but ice advanced well into the Lake Michigan basin (Larson and Schaetzl, 2001).

10

Figure 1-5: Major moraines in the Great Lakes region. Bolded moraine ridges are those labeled in Table 1.1. Dashed moraine ridges are from west to east: Mississinawa, Salamonie, and Wabash. The dashed moraine ridges record the gradual recession of the Huron-Erie Lobe during the Port Bruce Stade. Blue arrows show major meltwater pathways used to constrain glacial substages. Red box is study area

11

Figure 1-6: Union City Moraine position and 18.2 ka cal. yr BP isochrone. Isochrone and age assignment is based on till correlations from Monaghan and Larson (1986). The assignment of the Tekonsha Moraine as an ice marginal position has been called into question by Fisher et al. (2005). Study area shown in red.

Age constraints for the Port Huron Stade include radio-metrically dated organic acids deposited within soil in the Port Huron Moraine at 12,960 ± 300 14C yrs BP (~15.3

ka cal. yrs BP) (Blewett et al., 1993), and a spruce log buried in the correlative Wyoming

Moraine in 13,100 ± 110 14C yrs BP (16.0 cal. kyr BP) (Gravenor and Stupavsky,

1976).

12

Following the Port Huron Stade is another period of retreat known as the Two

Creeks Interstade. During the Two Creeks Interstade ice retreated out of the Lake

Michigan and basins. The Two Creeks forest bed in eastern and the Cheboygan bryophyte bed in Michigan provide age constraints for the Two Creeks

Interstade. Average radiocarbon dates for wood found at the Two Creeks forest bed are

12,400-11,800 14C yrs BP (~14.5 - 13.5 ka cal. yrs BP) (Broecker and Farrand, 1963;

Rech et al., 2012). Revised dates for the Cheboygan bryophyte bed average 11, 825 14C yrs BP (13.6 ka cal. yrs BP) (Larson et al., 1994).

1.5 Saginaw Lobe

First described by Leverett and Taylor in 1915, the Saginaw Lobe occupied much of central Michigan and northeastern Indiana, spanning from to an unknown position in Indiana. The retreat of the Saginaw Lobe is poorly constrained and interactions with adjacent lobes are unclear. It is interpreted that the Saginaw Lobe retreated earlier than adjacent Huron-Erie and Lake Michigan Lobes and the area was overridden by the adjacent lobes (Larson and Schaetzl, 2001). The chronology of the

Saginaw Lobe is based primarily on geomorphic correlations of moraines of the Saginaw

Lobe and its neighboring lobes and two catastrophic, geomorphic events; the Kankakee

Torrent (19.0 ka cal BP) (Curry et al., 2014) and the draining of (16.7 ka cal BP) (Burgis, 1970).

Evidence for the early retreat of the Saginaw Lobe comes from the truncated

Saginaw end moraines recognized by Leverett and Taylor (1915). Since 1915 researchers have found other lines of geomporphic evidence for the early retreat of the

13

Saginaw Lobe. Zumberge (1960) identified a crosscutting relationship between Huron-

Erie Lobe tunnel channels and Saginaw Lobe deposits in northern Indiana and southern

Michigan (Figure 1-7). Kehew et al. (1999) identified Saginaw Lobe tunnel channels

crosscut by Lake Michigan Lobe tunnel channels and later Saginaw Lobe tunnel channels

buried by Lake Michigan Lobe outwash fans in Kalamazoo County, MI (Kehew et al.,

2005) (Figure 1-7). Truncation of the Tekonsha Moraine with the Lake Michigan Lobe

deposits as suggested by Kehew et al. (2005) is further evidence to support the early

retreat of the Saginaw Lobe. However, the nature of the Tekonsha Moraine as a

recessional moraine has been called into question because of a continuous drumlin field across the moraine (Fisher and Taylor, 2002; Sjogren et al., 2002; Fisher et al., 2005).

Kehew et al. (2012) identified tunnel channels buried by Lake Michigan Lobe till north

of the Sturgis Moraine.

More evidence to support early Saginaw Lobe retreat can be found at the Huron-

Erie margin. Huron-Erie Lobe till above Saginaw Lobe till has been found in Lenawee

County, MI and Stuben County, IN (Zumberge, 1960), on the Iroquois Moraine (Gray,

1989), and in Lagrange County, IN (Brown et al., 1998) (Figure 1-7). Brown et al.,

(1999) found evidence of Huron-Erie Lobe fans being deposited on-top of Saginaw Lobe outwash. Dworkin et al. (1985) found Huron-Erie lobe incorporating Saginaw lobe drift in the interlobate area. Huron Erie meltwater channels cutting across Saginaw Lobe deposits provides additional evidence of an early retreat of the Saginaw Lobe (Kehew et al., 2012; Curry et al., 2014).

Horton (2015) dated lacustrine sediment cores of lakes from the Sturgis

Moraine to constrain the minimum age of the moraine. The oldest radiocarbon, and

14

Figure 1-7: Map of Wisconsinan age moraines modified from Zumberge (1960). Zumberge based this map on Frank Leverett’s unpublished field notes. Locations in Stuben County, IN and Lenawee County, MI where Huron-Erie Lobe till was found overlying Saginaw Lobe till are highlighted in red. Kehew et al., (1999) and Kehew et al., (2005) found evidence of Lake Michigan Lobe deposits overlying Saginaw Lobe deposits in Kalamazoo County, MI highlighted in red. Study area shown as blue box. therefore best minimum age for the Sturgis Moraine was found in Wall Lake and dated to

16,900 ± 180 cal. yrs BP (Horton, 2015). The minimum age of the Sturgis Moraine can therefore be correlated with kettle lakes dated at 16.8 cal. yrs BP on the Fort Wayne

Moraine (Glover et al., 2011). Although kettle lakes are a good source of dateable material the formation of kettle lakes results in a time lag. Sedimentary units in kettle lakes are frequently deposited during down wasting of ice blocks within the kettle basins.

Therefore a melt-out lag between deglaciation and radiocarbon ages can occur.

15

Dziekan (2017) quantified this melt-out lag in kettle basins in the Sturgis Moraine and Shipshewana Moraine of the Saginaw Lobe by comparing basal radiocarbon ages to basal OSL ages from the same cores. For example, in Thompson Lake on the Sturgis

Moraine Dziekan (2017) recorded a basal radiocarbon age at 14.8 ± 0.4 ka cal. yr BP and

OSL ages at 19.0 ± 0.8 ka and 20.4 ± 2.2 ka. Similarly in Stone Lake on the

Shipshewana Moraine a basal radiocarbon age of 16.0 ± 0.3 ka cal. yr BP and basal OSL ages 23.2 ± 1.0 ka and 23.6 ± 1.1 ka. OSL results suggest a melt-out lag time on the

Sturgis Moraine and Shipshewana Moraine kettle basins is 5,000 – 7,000 years.

Calculated melt-out times for the Sturgis and Shipshewana Moraines are significantly higher than the 1000 – 3000 years used in the deglacial reconstructions of Fullerton

(1980) and Dyke (2004). Dziekan’s (2017) OSL ages suggest that the Saginaw Lobe had retreated from the Shipshewana Moraine by 23.6 ± 1.1 ka and the Sturgis Moraine by

20.4 ± 2.2 ka (Figure 1-8).

Dzeikan’s (2017) OSL ages join a growing collection of optically stimulated luminescence (OSL) ages from Saginaw lobe deposits offering a different understanding of when the Saginaw Lobe retreated. In addition, Kehew et al. (2017) obtained four OSL ages from sandy sediment from collapsed Kalamazoo Moraine deposits of the Saginaw

Lobe ranging from 17.1 ± 2.1 ka to 19.9 ± 2.1 ka (Figure 1-8).

Southern Michigan is not the only place in the Great Lakes region where OSL provides earlier evidence for earlier retreat than the radiocarbon chronology records. Schaetzl et al. (2017) identified and dated glacial lacustrine sediment associated with a previously unknown called Roscommon in the

Houghton Lake basin of central Lower Michigan (Figure 1-8). This portion of the Lower

16

Figure 1-8: Deglacial isochrones of moraines based on radiocarbon ages from Fullerton (1980) and Dyke (2004). Blue stars represent OSL ages for deglaciation from Kehew et al. (2017) (mean of 19 ka; Kalamazoo Moraine), Dziekan (2017) (23 ka Shipshewanna Moraine and 19 ka Sturgis Moraine), and Schaetzl et al. (2017) (mean of 23 ka; Glacial Lake Roscommon). Figure modified from Horton (2015).

17

Peninsula of Michigan called the “High Plains” is interpreted as being covered by a sub- lobe of the LIS called the Mackinac Lobe (Schaetzl, 2001). The Mackinac Lobe moved into the region from the northeast and acted as a discrete lobe rather than part of the

Saginaw Lobe (Burgis, 1977; Schaetzl, 2001). Schaetzl et al. (2017) dated a delta forming in glacial Lake Roscommon using OSL with a mean age of 23.2 ± 1.2 ka. These ages suggest that the Mackinac Lobe had retreated considerably earlier than the rest of the ice sheet. Schaetzl’s (2017) and Dzeikan’s (2017) results suggest the ice lobes covering parts of Lower Michigan were in retreat much earlier than previously thought.

From the work of Dzeikan (2017) it appears the radiocarbon ages used to provide chronology for the Saginaw lobe may be too young (Figure 1-8). OSL offers the ability to date landforms when organics are absent. The OSL ages that exist suggests the retreat of the Saginaw Lobe occurred earlier than the neighboring Huron-Erie Lobe and Lake

Michigan Lobe. However, the extent and continuity of this retreat is not yet well constrained.

There is the possibility that the radiocarbon and OSL are both correct but that the radiocarbon dates record a second retreat after a readvance. Other evidence used to support episodic re-advance is the crosscutting relationship between tunnel channel and the Sturgis Moraine and crisscrossing tunnel channels (Fisher et al., 2005; Kehew and

Kozlowski, 2007; Kehew et al., 2012). To understand how crosscutting tunnel channels record a re-advance an understanding of tunnel channel formation is necessary.

18

1.6 A Hypothesis for Tunnel Channel Formation

Tunnel channels are elongated channelized, subglacial drainage ways formed by high velocity meltwater flows (Piotrowski, 1994; Clayton et al., 1999). Tunnel channels form parallel to ice flow direction and are useful for reconstructing ice flow. Often breaching end moraines, tunnel channels typically end in an outwash fan (Clayton et al.,

1999). The term , often used interchangeably with tunnel channels refers to a similar landform formed in similar conditions, but with slightly different morphology: the term tunnel channel refers to bank-full flow where water occupied the entirety of the passageway whereas, the term tunnel valley indicates that the water did not fill the passageway and instead the passageway was enlarged as the water migrated from side to side (Clayton et al., 1999). Also suggested as a process for forming similar morphology is collapsed pipes from groundwater piping or sapping beneath the (Clayton et al.,

1999). For the simplicity and the purposes of this study the term tunnel channel is used to reference both tunnel channels and tunnel valleys regardless of formation process as described by Clayton et al. (1999).

Morphologic characteristics useful in the identification of tunnel channels include: (1) channels that abruptly start or stop (2) anabranching of channels (3) convex- up longitudinal profiles (4) undulating profiles (5) reverse gradient to the ground surface

(6) chains of elongated lakes and underfit streams (7) cross cutting relationship with (8) channels occupied by eskers (Fisher et al., 2005). However, not all of these characteristics are found in each tunnel channel.

19

1.6.1 Incipient Tunnel Channel Model

The incipient tunnel channel hypothesis is based on hummocky tunnel channels found in and south-central Michigan (Sjogren et al., 2002) and Sweden (Peterson et al., 2018). The incipient model is used to explain the evolution of tunnel channels and explain the hummocky base of tunnel channels. Truncated sedimentary packages in channel walls in channel hummocks are explained as evidence that tunnel channels are eroded by subglacial meltwater (Sjorgen et al., 2002). Further, a lack of collapse features in excavated sections suggests hummocks are erosional remnants of a meltwater flow

(Peterson et al., 2018). Turbidity in the pressurized meltwater flow causes tunnel channels to be eroded unevenly forming a hummocky topography (Figure 1-9).

1.6.2 Palimpsest Tunnel Channel Hypothesis

Palimpsest tunnel channels form as blocks of stagnant ice remain in the tunnel channel as the glacier retreats (Clayton et al., 1999). The retreating glacier or neighboring glacial lobes then deposit outwash over the tunnel and dead ice. As the buried ice melts out it preserves the track of the tunnel channel with hummocky topography (Figure 1-10). The palimpsest tunnel channel hypothesis has been used to explain hummocky tunnel channels in outwash deposits found in Wisconsin and northern

Europe (Clayton et al., 1999) as well as, Saginaw Lobe tunnel channels in Michigan

(Kehew et al. 2005).

20

Figure 1-9: Development of incipient tunnel channels from Sjogren et al. (2002). All panels are in a developmental sequence (A) Glacier-substrate contact before release of meltwater. (B) Formation of hummocky topography. (C) Formation of hummocky tunnel channel. (D) Formation of a complete tunnel channel.

Figure 1-10: Development of palimpsest tunnel channels modified from Clayton et al. (1999). All panels are in a developmental sequence (A) subglacial tunnel channel is cut. (B) Meltwater stops flowing and the channel roof collapses. Outwash is deposited over the area burying dead ice. (C) The buried ice melts causing the outwash to collapse forming a partly buried tunnel channel.

21

1.7 Objective and Hypothesis

The overall goal of this thesis is to determine when the Saginaw Lobe retreated from northeastern Indiana. The hypothesis is the Mongo area is ice free by 23 ka. To test the hypothesis the following objectives are to be met:

• Surficial geologic mapping of the study area

• Creation of stratigraphic columns and cross sections

• Resolving the crosscutting relationship of tunnel channels and other landforms

• Chronology on the landforms

22

Chapter 2

Methods

2.1 Introduction

To test the hypothesis that the PRMC was ice free by 23ka, OSL and radiocarbon

ages were collected from sediment cores. The OSL ages provide a minimum age for

deglaciation and help elucidate the timing of landform formation. A digital elevation

model was used to map the landforms in the study area in detail and determine coring

sites. Ground penetrating radar (GPR) was used to investigate the subsurface

stratigraphy to examine crosscutting relationships. Sediment core analysis, outcrop

analysis, and hand augering were used to ground truth the mapping.

2.2 Maps and DEM

To map the study area high resolution LiDAR data was acquired from the Indiana

University Spatial Data Portal. The raw LiDAR data was collected in 2013 by the State

of Indiana with a 1.0 to 1.5 m nominal pulse spacing of resolution. The raw LAS LiDAR data was converted into a Digital Elevation Model (DEM) using Arc Catalog and

ArcGIS. The DEM was paired with digitized versions of: Orthophotography, county

23

level soil surveys, surficial maps of Lagrange County, IN (Figure 1-2, Brown et al.,

1998), and Stroh and Orland Township in Stuben County, IN (Brown and Jones, 1999a;

Brown and Jones, 1999b). A detailed surficial geology map was created of the study area to help delineate the spatial relationship of landforms.

2.3 Field Work

A Tractor mounted Geoprobe® is used to collect 3.5 cm diameter sediment cores.

The geoprobe uses a hydraulic and percussion system to drive a steel incased plastic

sleeve into the ground. A vibracore system is also used to extract sediment cores. The

vibracore uses a mechanical vibrator to drive 7.5 cm diameter aluminum piping into the

ground. Subsurface data is supplemented by the Indiana Department of Natural

Resources (IDNR) water well records database, and field observations. Due to

incongruity between water well logs, clays and diamicton in water well logs are

interpreted to be buried till. Information from sediment cores and water well logs is

paired with LiDAR data and ground penetrating radar (GPR) surveys to create geologic

cross-sections.

Optically stimulated luminescence samples are also collected from the geoprobe.

Quartz rich sediments are dated using OSL dating techniques. Organic carbon found in sediment cores are dated using radiocarbon techniques. A combination of the aforementioned methods will be used to reconstruct the deglacial chronology of the study area.

Borrow pit outcrops, road cuts, rail cuts, and river cuts were cleaned and examined to determine the lithology and sedimentology of the landforms when available.

24

Hand augering was used to ground truth stratigraphy where outcrops were absent. The

Pigeon River Fish and Wildlife Area (Figure 2-1) was covered on foot and much of the surrounding area was driven to examine morphology and check the DEM and soil survey interpretations.

Figure 2-1: Pigeon River Fish and Wildlife Area (PRFWA) highlighted in green. The PRFWA is an IDNR managed game preserve. Access to the property was unrestricted. Traversable land was covered on foot and all of the GPR surveys and geoprobing took place on the property.

2.4 Ground Penetrating Radar (GPR)

Ground penetrating radar (GPR) collects high resolution imagery of near surface sediments using radio waves (Annan, 2009). Although GPR can obtain information about the shallow subsurface it is limited to clean and gravel (Annan, 2009). Layers

25

of silt or clay can attenuate the signal making interpretation beneath these layers

impossible (Annan, 2009). GPR works well in dry gravel or sandy sediments or any other

earth material that is a poor conductor of electricity such as sand dunes (Bristow, 2009) and braided rivers (Bridge, 2009).

A pulseEKKO GPR unit was used to collect GPR data using a common-offset

reflection survey. GPR was collected using 50 MHz antenna and 100 MHz antenna. The

common-offset survey uses a single transmitter and receiver with a fixed spacing between

the two units (Annan, 2009). The antennas are moved incrementally and a data point is

taken at regular intervals (20 cm when using the 100 MHz antenna and 1 m when using the 50 MHz antenna) as radar waves are transmitted into the ground in all directions.

When hitting an object or medium with a different dielectric constant the wave will reflect. By determining the time that has passed between wave transmission and when the wave is picked up by the receiver it is possible to determine the distance to the reflector. A common midpoint survey was used to determine the velocity of the radar wave through the sediment. GPR transects were corrected for topography by using 1 m resolution LiDAR DEM to construct elevation profiles. Elevation profiles were spot- checked using a laser level. For more information of GPR methodology and theory see

Jol (2009).

2.5 Radiocarbon Dating

Glacial landforms in the Midwest have traditionally been dated using radiocarbon,

however, this requires the presence of organic carbon, which is uncommon in glacial

deposits. A sample was collected from a geoprobe core the sample was removed and

dried in an oven at 100°C for 24 hours. The sample was analyzed at the Woods Hole

26

Oceanographic Institution (WHOI) National Sciences Accelerator Mass

Spectrometry (NOSAMS) facility for AMS radiocarbon dating.

2.6 Optically Stimulated Luminescence (OSL)

Optically stimulated luminescence (OSL) is a novel technique that measures the amount of time that has passed since a sample of quartz or feldspar was last exposed to sunlight (Wintle and Adamiec, 2017). OSL has proven to be a useful tool for glacial and

Quaternary geologists. While organics are often difficult to find quartz and feldspar are found in most terrestrial surface settings.

Bleaching is the removal of trapped light in grains by exposure to heat or light and is essential to OSL dating as it resets or zeroes the luminescence of grains (Rhodes,

2011). Sediment grains found in some environments are completely bleached (i.e. eolian dunes) however in many glacial environments only partial bleaching occurs (Duller,

2006; Rhodes, 2011). To circumvent the partial bleaching of grains, small aliquot (SA)

OSL techniques were developed (Rhodes, 2011). SA OSL paired with the minimum age model (MAM) (a statistical analysis technique) allows for the dating of partially bleached samples.

A geoprobe was used to collect sediment samples for OSL dating. Sediment sampling tubes were covered in opaque tape and taken to the Indiana Geological and

Water Survey (IGWS) OSL laboratory for analysis. All OSL sampling is performed in a

light controlled laboratory. A schematic OSL sample collection is shown in Figure 2-2.

27

Figure 2-2: OSL sample collection from core. 32 total centimeters are sampled only 18 cm are processed for OSL. Dose rates are sent to an outside lab for calculation.

Thirteen to eighteen cm of medium-to-coarse grained quartz-rich sand is removed from

the sampling tube for OSL analysis. Five cm of sediment above and below OSL sample

is sent for dose rate measurement. The five cm below the lower dose rate measurement is

collected and sampled for moisture content. If there appears to be a change in ,

a moisture content measurement will be taken from sediment above the top dose rate

sample. Dose rate samples are sent to an external lab to be measured. Dose rate is

calculated using Aberystwyth University’s online dose rate age calculator; DRAC

(Durcan et al., 2015).

The wet chemistry involved in OSL sample preparation was performed at the

IGWS OSL lab in light controlled conditions. The OSL sample is wet sieved to separate

the > 255 µm fraction, 255-180 µm fraction, and the <180 µm fraction. The > 255 µm

fraction will be saved as extra grains for OSL dating. The < 180 µm fraction of the OSL

is discarded. OSL processing continues with the 255-180 µm fraction. The remaining

OSL sample is submerged in 15% HCl for > 12 hours to remove any carbonates. HCl is

decanted and the OSL sample is submerged in H2O2 for > 4 hours to remove organics.

H2O2 is decanted and the OSL sample is washed (3 – 4 submerges and decants with deionized water) to prepare for heavy liquid separation. Lithium metatungstate heavy liquids are used to separate feldspars (< 2.58 g/cm3) and heavier fraction (> 2.68 g/cm3)

28

from quartz. The process of separating feldspars includes centrifuging the sample and

using liquid nitrogen to freeze the heavier fraction while decanting the lighter fraction.

Heavy liquid separation occurs twice, once for each density separation. Feldspars

separated by heavy liquids are saved for feldspar infrared stimulated luminescence

(IRSL) in case needed. The OSL sample (quartz fraction) is then etched by a HF

treatment for 1 hour being stirred every 20 minutes to remove the outer 20 µm of the

grains to eliminate any alpha radiation and dissolve any feldspar grains still remaining.

For more information on OSL sample preparation see Aitken (1998).

Natural OSL sensitivity and regenerated OSL signal was measured by a Freiberg

Instruments Lexsyg smart OSL system. Small (1- 30 grain(s)) aliquots are placed on a stainless steel disc and inserted into OSL reader. Using Lexstudio software a shinedown test was performed on each of the aliquots to determine the natural OSL signal.

Luminescent aliquots with a strong fast component are then hot bleached (heated to 200

°C) and irradiated with a regenerative dose at 40 Gy (Gray), 80 Gy, 160 Gy, and 245 Gy, with a hot bleach occurring between each dose. A 40 Gy radiation dose is repeated to correct for sensitivity changes. OSL analysis is performed with RISØ Analyst software.

Dating glaciofluvial sediments with OSL is problematic as aliquots are rejected

and not used for analysis for a variety of reasons including: recuperation of OSL signal,

presence of a medium or slow component of OSL decay, if the grains appear saturated, if

the signal is too close to the background, or if there is simply no signal. A minimum age

model by Galbraith et al. (1999) was created to rectify partial bleaching of samples.

29

Chapter 3

Results and Interpretations

3.1 Introduction

The results of this study are used to determine when the Saginaw Lobe retreated from northeastern Indiana by using OSL to date outwash in the PRMC. Sediment cores were collected to investigate the stratigraphy of the PRMC and surrounding landforms and to provide stratigraphic control to geophysical surveys. GPR was used to image the subsurface to resolve crosscutting relationships. OSL and radiocarbon samples collected from sediment cores provide chronologic control for landforms sampled.

3.2 Surficial Geology

The glacial terrains of northeastern Indiana are among the most complex assemblage of geomorphic features in the eastern Midwest. The chronology of glacial landforms in this area is poorly understood due to the complex interplay between the

Saginaw Lobe and the Huron-Erie Lobe of the LIS.

30

This section presents the surficial geology map of the study area (Figure 3-1) and compares it with the interpretations of other authors. A detailed description of landforms with interpretations is provided.

3.2.1 Pigeon River Meltwater Channel

One of the most pronounced features in northeastern Indiana is the Pigeon River meltwater channel (PRMC). The modern Pigeon River is a fast, westward-flowing stream with a predominately gravel bed (Brown, 1998). The modern Pigeon River exhibits a meandering profile except where it flows into lakes; both manmade such as the Mongo

Millpond and natural depressions such as Pigeon Lake (Figure 3-2). The modern river has a width of less than 40 m except where dammed. The modern floodplain varies between 100 m and 500 m in width and is up to 2 m below the paleochannel.

The paleochannel or PRMC is incised into the outwash plain and through large outwash fans. The relief of the valley is typically 6-10 m below the surface of the outwash plain, but can occasionally be more than 30 m below the surface of adjacent fans. The width of the valley varies from 600 m up to 3 km. There are two morphologies within the PRMC. The western 33 km of the valley has a broad bottom with abandoned braided bars, braided channels, and terraces. The western portion of the PRMC grades into the Lima Plain where the channel form broadens and disappears (Figure 3-2). East of Hogback Lake the valley loses its characteristic valley form shifting to a pitted surficial expression (Figure 3-3). The pitted channel can be traced south-east across the

Fort Wayne Moraine complex for 17 km. The gradient of the pitted channel is uphill towards Hogback Lake. The broad, channel shaped portion of the PRMC west of

31

: Surficial geology map of the study area showing interpreted glacial terrains. Arrows Arrows terrains. glacial interpreted showing area study the of map geology Surficial : 1 - Figure 3 show

32

Figure 3-2: DEM of the PRMC. The Lima Plain extends off the image to the northwest. Black arrow shows flow direction.

Figure 3-3: Shift from subglacial meltwater flow to subaerial meltwater flow at the ice margin denoted by the white dashed line. Arrows show flow direction and ice margin. Subglacial flow characterized by hummocky channel. Subaerial flow characterized by braided bars and channels. White dashed line also shows local drainage divide.

33

Hogback Lake records subaerial drainage and the pitted portion of the PRMC east of

Hogback Lake records subglacial drainage through a tunnel channel. Meltwater flow

through the PRMC was to the west.

A tributary channel joins the PRMC from the south near the town of Mongo, IN.

This 30 km long channel called the Turkey Creek Meltwater Channel (TCMC) is

between 700 m and 1800 m in width and up to 135 m below adjacent uplands. Near the

mouth of the TCMC is an erosional remnant approximately 0.37 km2 in area and 30 m

higher than the bottom of the channel. South of little Turkey Lake is the tunnel channel

that fed the TCMC (Figure 3-3). The 8 km of the TCMC north of Little Turkey Lake has

a broad bottom and abandoned braided channels and bars. The northern portion of the

TCMC grades into the PRMC. South of Little Turkey Lake the tunnel channel has a

pitted or hummocky morphology with an uphill valley gradient to the northwest. The

shift in morphology at Little Turkey Lake is where meltwater drainage shifts from

subglacial drainage (south) to subaerial drainage (north). The TCMC records a

northwesterly meltwater flow from the glacier.

The PRMC has been interpreted as a westward flowing meltwater pathway for the

Huron-Erie Lobe (Zumberge, 1960; Brown et al., 1998). The meltwater that flowed

through the PRMC crosscuts some north-south trending tunnel channels expect where it ran (south-north) along a tunnel channel 4 km east of Mongo, IN. The expression of some tunnel channels can be seen crossing the floor of the PRMC, explained later as melt-out of buried ice after the PRMC had formed.

34

The PRMC formed in two stages, a high velocity and high discharge flow sourced

from beneath the glacier that eroded the valley and a depositional flow after erosion that

partially filled the valley with outwash. Evidence for a braided depositional flow includes the formation of lobate bars and abandoned braided channels. Large sediment supply and lack of vegetation make braided rivers a common feature in glacial environments.

Since deglaciation sediment deposition in the PRMC has slowed. With its sediment supply from the glacier gone the modern Pigeon River is now predominately erosional. The modern river has eroded less than 2 m into the surface of the PRMC and has done little to modify the landscape. Lakes and marshes can be found throughout the

PRMC; these lakes are in abandoned braided channels isolated from the meandering of the modern Pigeon River. These abandoned channels formed from higher discharge, glacially derived flows when the ice sheet was still proximal to the PRMC. Since becoming a meandering river the Pigeon River has modified less than 10% of the PRMC preserving much of the original deglacial landscape.

3.2.2 Huron-Erie Lobe Fans

Outwash fans are ice marginal, glacial fluvial landforms. As meltwater emerges from an ice margin a fan will develop as coarse material is deposited close to the meltwater portal and fine material is transported further (Bennett and Glasser, 2009). The

northern boundary of the PRMC erodes into the Brighton Fan. The apex of the Brighton

Fan appears near the edge of the PRMC just north of Mongo, but the true apex could

35

have been further south and eroded away by the flow that carved the PRMC. The fan

splays to the northwest and covers 25 km2 of the Lima Plain. The northern end of the fan is buried by smaller fans from the Sturgis Moraine. The Brighton Fan has a gradient of approximately 4 m/km. North-south trending depressions cross the Brighton Fan (Figure

3-4) are collapsed tunnel channels.

The Brighton Fan formed as an ice contact fan. The feeder channel for the

Brighton fan is not apparent. The Brighton Fan could have been fed by the same tunnel channel that fed the Flint Fan (Figure 3-1) and the PRMC, but at an earlier time. The

Brighton Fan grew westward from meltwater of the Huron Erie Lobe after the Saginaw

Figure 3-4: Crosscutting relationship between tunnel channels and Brighton Fan. Series of hummocky depressions in a north-south linear trend are interpreted to be tunnel channels and are discussed in section 3.2.4. Solid line shows ice contact margin of fan. Arrows show meltwater flow

36

Lobe vacated the space. The fan is composed of sand and gravel but portions of the fan

are capped by a thin loam diamicton interpreted by Brown et al. (1998) as a debris flow.

The Brighton Fan is part of an extensive line of similar fans associated with the Topeka

Fan System that extends 200 km across Indiana and Michigan (Gray, 1989; Brown et al.,

1998).

Near the head of the subaerial portion of PRMC is another outwash fan named after the nearby town of Flint, IN. The apex of the Flint Fan is near the edge of the

PRMC although it is truncated by meltwater flows that cut the PRMC. The fan radiates to the northwest over 24 km2 and has a gradient of 2 m/km. The fan appears to be

receiving meltwater and sediment from the same tunnel channel that would eventually

source the PRMC. Similar to the PRMC the Flint Fan is crosscut by north-south trending

tunnel channels.

A smaller fan is associated with the head of the TCMC. This smaller fan formed

at the same time as the Flint Fan as it has been truncated by the meltwater flows that carved the TCMC. This fan is called the Turkey Creek Fan due to its association with the

Turkey Creek Valley. The Turkey Creek Fan was sourced by the same tunnel channel that sources the TCMC.

3.2.3 Sturgis Moraine and Fans

North of the PRMC is the Sturgis Moraine, described in detail by Brown et al.

(1998), Kehew and Kozlowski (2012), Horton (2015), and Dzeikan (2017). The Sturgis

Moraine is a northwest-southeast trending moraine of the Saginaw Lobe. The moraine

37

and corresponding fan system spans from Centerville, MI to 3 km west of Orland, IN

(Figure 3-5). The moraine ridge is well defined south of the Michigan border. West of

Wall Lake near Orland, IN the moraine makes a ~45° bend sharply to the south (Figure

3-6) and may record a medial position between the Huron-Erie Lobe and the Saginaw

Lobe.

Figure 3-5: Sturgis Moraine fans and Brighton Fan outlined. Fans on the east side of the moraine are much smaller. Sturgis Moraine fans cover the Brighton Fan.

Figure 3-6: Bend in Sturgis Moraine west of Orland, IN. Arrow shows meltwater flow direction. Distal end of fan was built on stagnant ice. Topographic profile shows Sturgis Moraine ridge in tunnel channel. All values in meters. 38

The Sturgis Moraine has a crosscutting relationship with tunnel channels. Horton

(2015) interpreted tunnel channels to be cut through the Sturgis Moraine. However, the

moraine is not completely removed where it crosses tunnel channels as it would be if the

tunnel channels had eroded through the moraine. Further, there are places where the well-

developed moraine ridge is still found in the bottom of tunnel channels (Figure 3-6). This suggests the Sturgis Moraine was deposited on the tunnel channels followed by buried ice in the tunnel channels melting out to develop the depressions in the moraine (Figure 3-5)

Outwash fans that correspond to the Sturgis Moraine extend from the moraine ridge to the south. The Sturgis Moraine fans are much smaller than the Huron-Erie fans.

The largest Sturgis Moraine fan, the Sturgis Fan, has a lobate form and extends 6 km to the southwest from its apex (Figure 3-5). The southern edge of the Sturgis Fan is truncated by a smaller meltwater channel that empties into the Lima Plain. This smaller channel likely formed at the same time as the PRMC as meltwater cut across the moraine and drained eastward. Fans in the east are significantly smaller than Sturgis Fan and other western fans associated with the moraine. The gradient of these smaller fans is 4 m/km; similar to the 3 m/km of the Sturgis Fan. A small fan also builds to the southwest out of the bend in the Sturgis Moraine (Figure 3-6).

3.2.4 Tunnel Channels

The morphologic expression of tunnel channels north of the Sturgis Moraine and associated with the Saginaw Lobe have been described by Kehew et al., (1999),

Kozlowski (1999), Fisher and Taylor (2002), Kozlowski et al. (2003), Kozlowski (2004),

39

Fisher et al. (2005), Kehew and Kozlowski (2007), Kehew et al., (2013), Horton (2015),

and Dzeikan (2017). Many of these tunnel channels can be traced on either side of the

Sturgis Moraine. Tunnel channels south of the Sturgis Moraine have two different

orientations; north-south trending and northeast-southwest trending. Meltwater flow direction is presumed to be from the north or northeast. The traces of tunnel channels of either orientation can be found on both sides of the Sturgis Moraine, Brighton Fan, and

PRMC.

Three distinct tunnel channel morphologies exist in the study area: sinuous tunnel channels, parallel tunnel channels, and pitted tunnel channels. The most common morphology is sinuous channels (Figure 3-7). The sinuous channels are eastward of the other tunnel channel morphologies. These tunnel channels are discontinuous and have a hummocky profile of linked depressions. Width of the sinuous channels varies from

<100 m to 500 m. The longest of these channels extends 36 km although most are less than 10 km in length. Sinuous channels exist with both N-S and NE-SW orientations although the N-S orientation is more common. Except for the deepest of these channels

(the Otter Lake Channel, easternmost in Figure 3-7), the tunnel channels are crosscut by the PRMC. The depth of the surface of the Otter Lake Channel varies from 10 m below the uplands to no surface expression. There is no change in elevation along the bottom of

Otter Lake Channel as it crosses into the PRMC. There are no fans where the tunnel channel expression ends at the edge of the PRMC.

40

Figure 3-7: Sinuous tunnel channels outlined. Note different orientations and crosscutting relationships. The eastern most channel is the Otter Lake Channel.

Sinuous channels (Figure 3-7) appear partially filled where they cross fans. The

westernmost sinuous tunnel channel can be traced from north of the Sturgis Moraine,

through the Brighton Fan, and to the PRMC. The channel is thinner, less continuous, and

not as deep on the Brighton Fan suggesting partial burial by fan deposits (Figure 3-8).

The second type of channel has a parallel channel morphology. This channel is characterized by multiple thin parallel depressions separated by a higher medial strip.

Often the depressions are filled with water. In many places the expression of one or all of these depressions are lost. Where the parallel morphology is lost the channel takes on a pitted or undulating morphology similar to the sinuous channels. There is only one channel system with the parallel morphology in the study area. The tunnel channel

41

Figure 3-8: Tunnel channel through the Brighton Fan. Elevation profile from A to A’ shows the elevation of the bottom of the tunnel channel north of the Sturgis Moraine and south into the fan. The channel bottom is shallower and more hummocky where traced through the fan.

crosscuts the Sturgis Moraine, Brighton Fan, and its expression can be seen faintly in the

bottom of the PRMC (Figure 3-9).

The Third type of tunnel channel morphology is a pitted tunnel channel. This channel is the western most of the tunnel channels in the study area and is defined by its

hummocky and pitted surface expression (Figure 3-10). The channel at 2.25 km wide is

an order of magnitude wider than any other tunnel channel in the study area. The channel

42

Figure 3-9: parallel morphology tunnel channel. Note inner medial strip and where tunnel channel can be followed through the PRMC.

Figure 3-10: Pitted tunnel channel morphology outlined. Note the crosscutting relationship with the PRMC and two-track tunnel channel. “The Knob” is a 45 m gravel ridge interpreted as an outlet for the Ontario channel, as a crevice fill, or fill between two ice margins (Brown et al., 1999).

43

is near the town of Ontario, IN and is referred to as the Ontario Channel. The Ontario

Channel extends 21 km from north of the Sturgis Moraine southward to “The Knob.” In addition to being crosscut by the Sturgis Moraine, the Ontario Channel can also be traced through the PRMC, in which it is crossed by the parallel morphology tunnel channel.

The Ontario Channel is eroded into the Lima Plain and the channel surface depth is 9 m below the uplands. In the PRMC the Ontario Channel surface depth is only 4 m below the surface of the PRMC deposits. However, a line of depressions and hummocks can still be found. This tunnel channel morphology is similar to the morphology of tunnel channels that sourced the PRMC and TCMC. At the mouth of the Ontario channel is a 45 m tall gravel ridge called “The Knob”. “The Knob” has been interpreted as a modified outwash fan for the Ontario channel, a crevice fill, or fill between two ice margins

(Brown et al., 1999).

3.2.5 Eskers

Unlike the tunnel channels that sourced the PRMC and TCMC none of the north- south trending tunnel channels have subaerial meltwater channels or fans associated with them. The only depositional landforms associated with the tunnel channels are the eskers found within the Otter Lake Channel and in parallel tunnel channels.

Eskers are common landforms in glaciated systems, and are often found within tunnel channels (Shreve, 1972), and generally form during the terminal stages of glaciation (Shreve, 1985). Where eskers are found within tunnel channels they indicate two different stages of flow within the tunnel channel; an initial flow to erode the

44

channel, followed by a waning flow and deposition of the esker (Kehew, 2012). If the ice above the esker stagnates and becomes dead ice the esker may be draped by a thin layer of melt-out till (Kehew and Kozlowski, 2007). In the study area there are two tunnel channels with discontinuous eskers (Figure 3-11).

Discontinuous eskers are found within the Otter Lake Tunnel Channel and the parallel tunnel channels. Eskers do not extend the entire length of the tunnel channels, but instead form short 150 – 500 m long segments. None of the eskers can be traced through the PRMC however an esker can be traced up to the edge of the PRMC in the parallel tunnel channels. In the Otter Lake Tunnel channel the esker is in the hummocky portion of the tunnel channel and the uplands between the hummock depressions.

However, the esker is never higher than the outer edges of the tunnel channel.

Borrow pits and road cuts on the eskers were visited (Figure 3-11). The borrow pit excavation (Figure 3-12) showed a gravel-cored esker with a draping diamicton. A gravel lag existed between the gravel and sand of the esker and the diamicton. The gravel within the esker showed a few examples of imbrication. The diamicton was sandy and contained large faceted and striated clasts.

45

Figure 3-11: Eskers found within tunnel channels in the study area. Eskers are highlighted in yellow. (A) Eskers within the parallel tunnel channel. (B) Eskers within the Otter Lake Tunnel Channel.

46

Figure 3-12: Borrow pit esker outcrop from location shown in Figure 3-11. Esker has a gravel core with some imbricated clasts. A massive sand covers the gravel core. The landform is draped with a sandy diamiction. Clasts in the diamiction are faceted and striated. Most clasts are sized but are up to 1 m in diameter. A thin discontinuous fine gravel lag exists between the sand and diamiction. Shovel in top panel is 1.5 m.

47

3.2.6 Ice-Walled Lake Plains

Ice-Walled Lake Plains (IWLP), also known as rim-ridge , are common deglacial landforms and are often found in hummocky topography (Clayton et al., 2008).

IWLPs are identifiable because of their raised, round shape. Many IWLPs have an outer rim ridge of sand and gravel or till around the raised shape. Typically containing lacustrine sediment IWLPs are explained as former lakes in holes on stagnant ice

(Gravenor and Kupsch, 1959; Eyles et al., 1999). There are two models to explain their formation (1) subglacial pressing (Stalker, 1960; Eyles et al., 1999) and (2) slumping and inversion of supraglacial sediments with stagnant ice (Johnson and Clayton, 2003;

Clayton, 2008).

IWLPs are found in the study area east of the Turkey Creek Fan and north of the

Sturgis Moraine in till plains associated with both the Saginaw Lobe (Sturgis Moraine) and Huron-Erie Lobe (Turkey Creek Fan). The IWLPs were identified solely on their morphology and were neither investigated nor cored in this study. However, the IWLPs identified north of the Sturgis Moraine were also identified by Horton (2015). IWLPs are indicative of stagnant ice.

3.2.7 Mongo Dunes

Inland dunes are an excellent landform for reconstructing paleoenvironments.

Following deglaciation the rapidly changing climate and unstable surfaces are ideal for

the formation of large dune fields (Arbogast et al., 1997). Dunes are ideal candidates for

48

optically stimulated luminescence dating (OSL) as the sediments are homogeneous and

were exposed to sunlight during formation (Rhodes, 2011).

Located in the PRMC is the ~10 km3 Mongo Dune Field (Figure 3-1). Dune

morphology varies from windrift dunes to rake-like and imbricate complexes that record westerly winds (Fisher et al., 2019).

Previous OSL dating of the Mongo dunes suggested two eolian events. An older period of dune activity centered around 14.1 ka and a younger event centered around 12.2 ka (Fisher et al., 2019). The older dunes are located on the floor of the PRMC while younger dunes are located on the uplands. The older event gives a minimum age of 14.4

± 0.5 ka for deglaciation (Fisher et al., 2019). The younger dune activity around 12.2 ka correlates with the Younger Dryas climatic event and an increase in eolian activity throughout the southern Great Lakes (Campbell et al., 2011; Kilibarda and Blockland,

2011; Fisher et al., 2015; Colgan et al., 2017; Fisher et al., 2019).

3.2.8 Landform Relationships

The interaction of two ice lobes in the study area has created a complex

relationship of glacial landforms. Crosscutting relationships between tunnel channels and

other landforms complicates attempts at determining a deglacial chronology. However,

some of those relationships can be resolved.

The PRMC crosscuts some tunnel channels but not others. The channels that are

crosscut by the PRMC are not as deep as channels that have depressions through the

49

PRMC. There are two possible explanations for this: (1) when the PRMC was incised tunnel channels contained buried ice. In some cases buried channels with ice were eroded away, while other tunnel channels with ice were more deeply incised and the PRMC did not incise deeply enough to erode them. (2) Tunnel channels were formed after the

PRMC with some channels ending at the PRMC. The first explanation is favored because the flow that carved the PRMC eroded the Brighton Fan which was deposited on a buried ice filled tunnel channel (Figure 3-8). This suggests the PRMC was incised into the tunnel channels. Secondly, there are no fans preserved at the mouth of tunnel channels where they end at the PRMC suggesting that no material has been carried through them after the formation of the PRMC.

The relationship between the two orientations of tunnel channels is also complicated. They formed either in different glacial advances or during a reorientation of the Saginaw Lobe’s surface profile. The presence of an esker in the parallel morphology tunnel channel where it crosscuts the Ontario Channel suggest that the Ontario channel has to be older. The size of flow that had to form the Ontario channel would have eroded the esker if the Ontario channel was younger. This relationship is projected to all tunnel channels in the study area, therefore the N-S trending tunnel channels such as the Ontario

Channel are older than parallel morphology tunnel channel and other NE-SW trending tunnel channels.

50

3.3 Sediment Cores

The surficial geology map (Figure 3-1) was used to guide sediment core collection. Sediment cores were collected to determine the stratigraphy of the PRMC and surrounding landforms and to provide stratigraphic control to geophysical surveys. Cores were collected in strategic locations where material useful for dating was expected.

Depressions within tunnel channels were cored to reach lower stratigraphy. OSL and radiocarbon samples were collected from the sediment cores. Fourteen locations were cored using the geoprobe and vibracore systems (Table 3.1, Figure 3-13). All cores were recovered from PRFWA property.

As geoprobe cores were collected if the sediment was acceptable for OSL dating a second core was taken less than 10 cm from the original core site. Six of the geoprobe locations were cored twice in this manner. Sediment cores were taken to The University of Toledo for analysis. Geoprobe core recovery varied from 40% to 90%, averaging 60%.

Recovery is low due to coarse grained sediment and high water content. In contrast vibracore recovery was 90-100%.

Cores PR-1, 2, 6, 7, and 11 (Figure 3-14) were taken from the bottom of the

PRMC and consist of beds of sand and gravel beneath well-sorted sand. Clast are well- rounded coarse and often the beds fine upward from sand to pebbles. Clast size was limited to the diameter of the core barrel. The sand and gravel units along the bottom of PRMC is similar to other sediments interpreted as glacial fluvial outwash (Rust and Romanelli, 1973; Brodzikowski and Van Loon, 1987). Sand and gravel units are interpreted to be outwash deposited in the flows of the PRMC. All of the

51

Table 3.1: Sediment cores collected in this study.

UTM coordinates (16T) Core ID Northing Easting Lat° Long° Surface Elevaiton (m a.s.l.) PR-11 41.68633 -85.3021 41°41’10.8”N 85°18’07.6”W 277 PR-21 41.67545 -85.3021 41°41’31.6”N 85°13’40.1”W 283 PR-3 41.66523 -85.1984 41°39’54.8”N 85°11’54.2”W 299 PR-4 41.66508 -85.1985 41°39’54.2”N 85°11’54.6”W 299 PR-51 41.66644 -85.1984 41°39’59.2”N 85°11’52.2”W 296 PR-61 41.66719 -85.1920 41°40’01.9”N 85°11’31.2”W 285 PR-7 41.66770 -85.1787 41°40’03.7”N 85°10’43.3”W 288 PR-8 41.69487 -85.2880 41°41’41.5”N 85°17’16.8”W 289 PR-91 41.68346 -85.3496 41°41’00.5”N 85°20’58.6”W 275 PR-101 41.68313 -85.3547 41°40’59.3”N 85°21’16.9”W 277 PR-11 41.68712 -85.2934 41°41’13.6”N 85°17’36.2”W 275 PR-121,2 41.68232 -85.2394 41°40’56.4”N 85°14’21.8”W 287 VC-1 41.68290 -85.3522 41°40’58.4”N 85°21’07.9”W 273 VC-2 41.69132 -85.1906 41°41’28.8”N 85°11’26.2”W 287 1 Sampled for OSL 2 Sampled for radiocarbon

Figure 3-13: Sediment cores collected in this study. Circles are geoprobe cores and triangles are vibracores.

52

Figure 3-14a: Part 1 of core logs of sediment cores taken from the PRFWA property. For core locations refer to Figure 3-13. Individual logs discussed in text.

53

Figure 3-14b: Part 2 of core logs of sediment cores taken from the PRFWA property. For core locations refer to Figure 3-13. Individual logs discussed in text.

54

PRMC cores contain well-sorted sand at the top. The contact between the lower sand and

gravel units and this well-sorted sand is abrupt. This sand is interpreted as eolian sand

from the Mongo dune fields. Cores PR-1, 2, and 11 sample the Mongo dunes directly

and no evidence of a paleosol was found. Core PR-1 has four units and reaches some of

the lowest stratigraphy of the PRMC. The upper units in core PR-6 contain more silt. It

is possible that these upper units in PR-6 are: modern alluvium because of the proximity of the core to the Pigeon River, record loess deposition, or sedimentation in calmer waters as the outwash aggraded.

Cores PR-3, 4, and 5 were taken near the meltwater terrace south of the PRMC

(Figure 3-1). PR-3 and 4 are from the outwash plain above the terrace and both are massive outwash. PR-5 is taken from the PRMC terrace and has two sand and gravel

units that are better sorted than PR-3 and 4 with the lowest unit in the core is a fining

upward sequence from medium pebbles to granules.

Core PR-8 was taken in a sinuous tunnel channel that crosscuts the

Brighton Fan. PR-8 contains well-rounded to sub-rounded sand and gravel. Sand size is

medium to very fine. The variability and thickness of sediment unitary units in PR-8 and

presence of a silty unit is similar to what would be expected in an outwash fan where

flows are variable and sand and fines are deposited between coarser units (Krüger, 1997).

Core PR-9 was taken in a tunnel channel depression within the PRMC. The

lowest unit of PR-9 is pebbly sand overlain by silty sand and gravel that in turn is capped

by a mottled, very-fine, pebbly sand unit. The top meter of PR-9 is fine sand interpreted

to be eolian.

55

Core PR-10 was taken atop the medial strip of the “two-track” tunnel channel.

The lower unit is gravel with angular clasts and interbeded sand. The top two meters of

the core is medium sand interpreted to be eolian.

PR-12 was taken in a borrow pit in the side of the meltwater channel and is the

only core with organic material. Pebbles within the massive gravel are rounded.

VC-1 was taken in a depression within the parallel channel (Figure 3-9). VC-1

contains coarse, well-rounded sand and gravel in a fining upward sequence. A thin peat

layer is capped by sandy peat. The contact between the peat layer and sandy peat is

interpreted to be the pre-settlement surface.

VC-2 was taken in a depression in the Otter Lake Channel (Figure 3-7). The depression contains a man-made lake. The lower unit (196-230 cm) is a dense, sandy diamicton. This unit contains cobble sized gravel in an unsorted matrix of compacted sand, silt, and clays. This diamicton is interpreted to be a basal till that resembles to the

Newbury Till found at depth in the area (Brown et al., 1998). The Newbury Till is a silty diamicton from a northern source that was deposited during the earliest part of the Late

Wisconsin (Brown et al., 1998). The next 84 cm (112-196 cm) is well rounded and

bedded sand and gravel. This unit is interpreted to be tunnel channel fill. The next two units (51-112 cm) are a massive clayey sand and gravel. This unit formed as the channel collapsed. And the unit above mixed with sand and gravel bellow. The upper 51 cm is a massive sandy clay interpreted to be lacustrine sediment that developed after damming

and the upper 20 cm is peat.

56

3.4 Ground Penetrating Radar (GPR)

While sediment cores provide information on the near surface stratigraphy of various landforms penetration depth was limited to only a few meters. To more

effectively deduce sediment thickness, geophysical transects were paired with water well

logs from the IDNR to develop geologic cross sections and determine the thickness of

sediment.

Ground penetrating radar (GPR) was used to collect 4370 m of survey. 1470 m of

GPR were collected using 50 MHz antenna and 2900 m of GPR were collected using 100

MHz antenna (Figure 3-15). GPR was used predominately within the PRMC because of

suitability of the resistive sediment for penetration. One common midpoint survey was

collected to determine the velocity that the radar waves traveled through the sediment.

Sediment cores and water well logs at the endpoints of GPR transects were used as

Figure 3-15: GPR transects in the study area.

57

stratigraphic controls. Important GPR transects and interpretations are discussed below.

The remaining GPR transects with interpretations are available in Appendix A.

GPR was used on the dune field to look for paleosols and the contact between the

eolian and outwash. GPR transects PR-01, PR-02, and PR-03 cross parabolic dunes in the Mongo Dune Field. Transect PR-01 is transverse over the arms of the dune.

Transects PR-02 (Figure 3-16) and PR-03 are parallel to the central axis of the dune and over the nose of the dune. The GPR reveals continuous and discontinuous reflections parallel to the surface. The signal penetrates to a depth of 2-3 m where it quickly begins to attenuate due to silt within the outwash. Contact between eolian and outwash is

unclear in this transect.

Transect PR-04 (Figure 3-17) and PR-05 are across the PRMC terrace down to

the floor of the PRMC. Transect PR-04 contained a hummocky facies of mostly

discontinuous reflectors with a consistent attenuation after 4-6 m of penetration. Long,

continuous reflectors that do not follow the surface expression are apparent in the profile

near the 30 m mark. These reflectors are interpreted to be the channel scour and fill of

braided bars. There is no clear contact between terrace deposits and meltwater channel

deposits in the radar profile.

PR-08 (Figure 3-18) surveys the PRMC scarp to the modern Pigeon River. The radar facies in PR-08 is wavy with hummocky discontinuous reflectors parallel to the

58

Figure 3-16a: Location of GPR transects on Mongo Dunes on hillshade.

Figure 3-16b: GPR transect PR-02 of the Mongo Dunes with interpretations. Note the interpreted cross bedding in the eolian deposits. Prevailing wind direction from the west.

59

Figure 3-17a: Location of GPR transects PR-04 and PR-05 on hillshade.

Figure 3-17b: GPR transect PR-04 with interpretations. Transect descends from PRMC terrace onto the lower PRMC. Note how there is no change in penetration depth as GPR crosses the terraces.

60

Figure 3-18a: Location of GPR transects PR-08 on hillshade. Geoprobe core PR-12 taken from borrow pit directly north is shown as green circle.

Figure 3-18b: GPR transect PR-08 with interpretations. Transect from near the modern Pigeon River to PRMC scarp. Note stratigraphic controls. PR- 12 is a geoprobe core collected in this study. 50374 is a water well log.

61

surface. Radar penetration is 6-8 m with the deepest penetration in the south. One

continuous reflector can be seen through the radar transect and is interpreted as the water

table. This radar facies is interpreted as silty sand and gravel and provides a minimum

thickness of 9 m of outwash.

GPR transects PR-09 and PR-10 are from the Ontario Channel where it crosscuts

the PRMC. PR-09 (Figure 3-19) reveals one radar facies; a hummocky facies that

attenuates at a depth of 6-8 m interpreted to be sand and gravel. Convex continuous

reflectors in this radar facies resolves a collapse feature interpreted to be a kettle depression. A second facies is revealed in the northern portions of the PR-09 transect.

This facies has parallel continuous reflectors interpreted as undeformed outwash. The kettle and collapsed beds in PR-09 suggest that the beds where once supported by buried ice that melted out forming the depression at the surface. Melting of ice could explain the crosscutting relationship of the tunnel channel morphology and is discussed in detail in section 4.2.

To image across the entire meltwater channel, transect PR-13 crosses the narrowest portion of the PRMC. The sand and gravel of outwash fan deposits and tunnel channels are also suitable for GPR and GPR transects were used to image the uplands adjacent to the PRMC. Transect PR-11 images a small portion of the pitted tunnel channel and transect PR-19 images a kettle within the same channel. PR-12 images the

Flint Fan near where it is cut by the PRMC. GPR imaging of the sinuous tunnel channels can be seen in PR-18.

62

Figure 3-19a: Location of GPR transects PR-09-11 on hillshade.

Figure 3-19b: GPR transect PR-09 with interpretations. Transect is along the hummocky portion of the PRMC. Note stratigraphic control. PR-9 is a geoprobe core collected in this study. Deformed beds suggest the hummocky topography formed as a result of the melting of buried ice. Stratigraphy is undeformed beneath braid bars on far right of the transect.

63

3.5 Stratigraphy

Data from sediment cores and GPR transects are used to reconstruct the

subsurface stratigraphy. Water well logs are included with shallow surface stratigraphy

to resolve deeper stratigraphic relationships and provide relative dating on landforms not

directly sampled. Units of sand, sand and gravel, and gravel described in the water well

logs are surmised to be units of outwash. Diamicton and clay units described in water

well logs are surmised to be units of till or loamy soils.

Four landforms were sampled using a geoprobe and vibracore to provide shallow

stratigraphy; they include: an outwash plain, two different tunnel channels, Mongo

Dunes, and the PRMC (Figure 3-20). The outwash plain south of the PRMC and east to

the TCMC (Figure 3-1) is massive sand and gravel and similar sediments are interpreted to be glacial fluvial outwash (Rust and Romanelli, 1973; Brodzikowski and Loon, 1987).

The geoprobe recovered 1-2 m of outwash, but nearby water well logs suggest the sand and gravel unit continues to a depth of 20 m (Figure 3-21). The outwash plain is the surface that the PRMC is eroded into and fans are deposited on which make it the oldest exposed surface in the study area.

Two individual tunnel channels were sampled using the vibracore and geoprobe.

Sediment in tunnel channels is bedded sand and gravel units capped by either lacustrine or eolian infill. Tunnel channels are eroded into and often through the Newbury Till

(Figure 3-22). In some cases, outwash fan deposits partially fill-in tunnel channel depressions (Figure 3-8) but distinguishing between outwash fan and tunnel channel deposits is not possible from available cores.

64

Figure 3-20: Schematic of near surface stratigraphy developed from cores across 15 km. Core logs are simplified versions of those in Figure 3-14. Vertical scale of cores is preserved. Horizontal ordering of cores is correct but the spatial scale is not preserved. Dashed lines do not represent topography but connect landform surfaces. Note how the PRMC is likely eroded through the diamicton at the bottom of VC2.

Figure 3-21: Cross section across the PRMC. From GPR transects and water well logs. Topographic profile is from DEM. Facies are: Mongo Dune sand (md), outwash plain (op), lacustrine (lac) Pigeon River Meltwater Channel outwash (pro) Newbury Till (nt) pre-Newbury outwash (o).

65

Figure 3-22: Cross section across the Otter Lake Tunnel Channel. Stratigraphy from vibracore and water well logs. Topographic profile is from DEM. Facies are: tunnel channels/lacustrine sediment (tc/lac) outwash plain sand and gravel (op), Newbury Till (nt), pre-Newbury outwash (o).

The PRMC channel, terrace, and scarp were all sampled using the geoprobe. The

PRMC main channel deposits are predominately cyclical, fining upward, sand and gravel

units. Silty sand, gravel beds, and sorted sand beds are also common within PRMC

deposits. Variable sediment size and cyclic variability is similar to glacial-sourced

braided river facies summarized in Miall (1977). The fining upwards sequences in the

PRMC record waning flows and the deposition of fines indicate there were abandoned

pools. Sand and gravel deposited above finer units indicates that flows were variable.

The PRMC terrace is 2 m above the PRMC channel. The PRMC terrace is composed of a

silty sand and gravel unit buried by a cleaner sand and gravel unit that is interpreted as a

braided river deposits. The PRMC is incised 10 to 20 m through the Newbury Till and

into outwash beneath the till (Figure 3-21 and 3-23).

66

The Mongo Dunes are constructed of a medium-fine, well-sorted sand. Geoprobe cores revealed that many depressions are also filled with this sand and a thin sand sheet is found across the floor of the PRMC.

Some water wells showed diamicton or clay at the surface which could suggest a second till. However, field observations and hand auguring near wells 32129 and 357346

(Figure 3-21) and well 55807 (Figure 3-22) and at other water well sites in the study area found a silty sand and gravel which is in agreement with the sandy loam and sandy loams described by the soil survey. The fines in the soil are the result of waning meltwater flows and mineral weathering since deglaciation and not a second till at the surface.

Figure 3-23: Cross section along the floor of the PRMC from water well logs. Topographic profile is from DEM. Facies are: Pigeon River Meltwater Channel outwash (pro) Newbury Till (nt) pre-Newbury outwash (o).

67

3.6 Radiocarbon Age

One radiocarbon sample was collected from geoprobe core PR-12 (Figure 3-14)

through the bottom of a borrow pit dug into the scarp of the PRMC (Figure 3-18a).

Estimating the amount of the material removed from the borrow pit to be approximately

3.5 m, and a sample depth in the core of 0.7 m, the sample was buried by more than 4 m

of outwash. The charcoal has an age > 46,200 14C yrs BP (Table 3.2) which is beyond

the capabilities of radiocarbon dating. An infinite age from the charcoal in the outwash is

not useful as it can be interpreted multiple ways – two are: (1) remobilized wood from

older material redeposited within Late Wisconsinan outwash or (2) the outwash is older

than 46 ka 14C yrs BP and was deposited during the Wisconsinan or an earlier

glacial event.

Table 3.2: Radiocarbon Results.

ID Type Fraction FM Age Age Err d13C Modern Error IGWS Charcoal 0.0015 0.0017 > 46200 N/A -24.58 PR12-1A ORG1

3.7 Optically Stimulated Luminescence (OSL)

This study relies heavily on using the OSL dating method to provide chronologic control for the studied landforms. Sample locations are provided in Table 3.3, supporting data can be found in Table 3.4, and OSL ages are provided in Table 3.5. OSL samples from outwash have large errors due to the small number luminescent aliquots. The sample error was further compounded by the statistical error associated with the

68

Table 3.3: OSL sample locations

Table 3.4: Concentration of dosimetrically significant elements

Table 3.5: OSL ages and related results

69

minimum age model. Large errors on OSL ages make it difficult to assign precise ages to the outwash deposits without processing additional aliquots.

Based on mapping and analysis of cores presented earlier in this thesis, OSL samples IGWS 48, 58, 60, 61, 149, and 150 are from outwash, and samples IGWS 59 and

IGWS 153 are eolian deposits. A minimum age model was used on IGWS 59 even though an eolian deposit would warrant the use of a central age model. This is because a number of grains were older than the bulk of the sample and were interpreted to be incompletely bleached (Figure 3-24). Partially bleached grains could bias the sample because some older grains from the underlying outwash may have been mixed into the eolian sand by processes such as soil heave and bioturbation. A central age model was also chosen for IGWS 149 even though it was collected from an outwash unit. The central age model was used because of location of the IGWS 149 sample in the stratigraphic column (the top of a presumed buried surface). The sample was taken from the upper 20 cm of outwash unit that was buried by 1 m of eolian sand. Through bioturbation and soil heave IGWS 149 was bleached due to its proximity to the surface of the outwash before being buried by the migrating dunes. Therefore, sample IGWS 149 records dune activity and has the same age as IGWS 153. For all minimum age calculations an overdispersion of 20% was used when using the minimum age model. An overdispersion of 20% is normal for OSL (Galbraith et al., 1999) and a dose recovery performed on other northern Indiana samples show that 20% is appropriate (Murray and

Wintle, 2003; Antinao-Rojas, personal communication, 2019).

70

Figure 3-24: Radial plot of IGWS 59. Individual aliquot ages plotted against standard error. A minimum age model was used on IGWS 59 because of numerous poorly bleached grains aged between 20 and 40 ka. Dashed line shows minimum age estimate of 12.5 ka.

OSL ages are either from outwash within the surficial boundaries of the PRMC or

Mongo Dunes. OSL ages from outwash within the PRMC are: 15.7 ± 2.7 ka, 17.1 ± 3.0

ka, 23.3 ± 5.8 ka, 23.4 ± 4.4 ka, and 33.8 ± 7.4 ka from three cores PR-1, 2, and 10

(Figure 3-14). Where multiple OSL ages are from the same core younger OSL ages are stratigraphically higher in the core. When the OSL ages on PRMC outwash are plotted

(Figure 3-25) there are three possible ages for PRMC activity: early around 33.8 ka, middle around 23.4 ka, and late centered on 16.4 ka.

An age of 33.8 ka for meltwater activity in the PRMC is not likely as ice reached its maximum extent in the Great Lakes region around 24.0 ka (Loope et al., 2018), it is

71

Figure 3-25: Age distribution of OSL samples collected. Dashed lines show one possible grouping of OSL ages. Early ages are from buried outwash. Middle and late ages record meltwater activity in PRMC. Recent ages record dune activity.

possible this sample has not been completely bleached, and additional aliquots of this

sample would result in a more precise age. An alternative explanation for this sample is

that it was collected from the outwash beneath the PRMC however, there is no clear stratigraphic contact in the core to suggest this. Additionally, the 33.8 ka sample could contain an OSL signal from older outwash mixed in with the PRMC deposits during the early stages of deposition.

The OSL samples that are aged 17.1 ka and 15.7 ka are young and were likely deposited when ice was no longer near the ice margin (recorded by the Flint Fan) as the radiocarbon chronology suggests the Huron-Erie Lobe ice margin was east of the

Defiance Moraine at the time (Figure 1-8). Instead, these samples could be fluvial sediments that reworked older outwash, a precursor to the modern Pigeon River.

Therefore, OSL ages from PRMC deposits record the upper and lower limits of meltwater activity through the PRMC between ~29 ka and ~17 ka. A mean age on all

72

PRMC sample OSL ages is 19.9. However, OSL ages suggest that there was possibly a peak in meltwater activity at ~23.4 ka.

OSL ages that record eolian activity are: 10.6 ± 0.8, 10.9 ± 0.9, and 12.5 ± 1.5.

All OSL samples are from dunes on the floor of the PRMC. The 10.6 ka sample is from the top of outwash directly below the dune dated to 10.9 ka. Grains in the sample appear to have received enough sunlight due to bioturbation and soil processes to become well bleached until the dune or sand sheet covered the outwash.

73

Chapter 4

Discussion and Conclusions

4.1 Introduction

This chapter will integrate the stratigraphy and chronology discussed in Chapter 3 to reconstruct the deglacial chronology of the PRMC and surrounding landforms. The main objectives that will be answered are: (1) when the PRMC was active, (2) when the

Mongo Dunes were active, (3) the relationship between the PRMC and tunnel channels and, (4) when did the Saginaw Lobe retreat. Providing answers to these questions will assess the hypothesis that the Mongo area is ice free by 23 ka. The chapter will finish by discussing the implications of this study and future work.

4.2 Stratigraphy

A conceptualized and simplified stratigraphy of the PRMC and surrounding landforms is shown in Figure 4-1. This conceptual model was built from sediment cores, water well logs, and GPR discussed in Chapter 3. Older outwash at the bottom of the cross section is interpreted as proglacial outwash associated with the ice that deposited the Newbury Till (Brown et al., 1999). As ice retreats following the Nissourian Stade the

74

Figure 4-1: Conceptual stratigraphic cross section of the PRMC. Vertical thickness of units not drawn to scale.

outwash plain (op) is deposited above the Newbury Till. Glacial fluvial landforms such

as the PRMC and tunnel channels were eroded before flow waned transitioned to a

braided river environment leading to outwash accumulation. The Brighton Fan partially

buries the outwash plain.

Collapsed beds resolved in GPR transect PR-09 reveal that the morphology of palimpsest tunnel channels were preserved by buried ice in a method similar to that described by Clayton et al. (1999) (Figure 4-2). Tunnel channels were eroded and partially filled with ice. As the glacier retreated sediments buried the ice within tunnel channels. Ice in tunnel channels was preferentially preserved because it was insulated by thicker sediment than surrounding ice. As the temperature increased and buried stagnant ice began to melt. As ice melted sediments above tunnel channels were no longer supported and collapsed into the tunnel channels revealing the morphology of

75

Figure 4-2: Sequence of events to form partially buried palimpsest tunnel channels in the study area. (A) Meltwater erodes tunnel channel into substrate beneath glacier. (B) Meltwater flow wanes and sand and gravel is deposited within the tunnel channel. (C) When meltwater flow ends ice fills the tunnel channel. Eskers may form at this time. (D) Glacier stagnates and ice melts from the top down and ice becomes buried by outwash. Buried ice in tunnel channel is insulated by the thickest sediments preserving the ice longer than the rest of the glacier. At this time the PRMC erodes through the study area. (E) Buried ice in tunnel channel melts and outwash above collapses causing the surface topography to record location of buried tunnel channels.

76

the palimpsest tunnel channels. Post glacial deposits including the Mongo Dunes, the

Pigeon River alluvium, and lacustrine deposits in depressions further modify and cover

the Wisconsinan landforms. The cross section (Figure 4-1) will be used to discuss the absolute chronology and relative dating of landforms in this chapter

4.3 Geochronology

The one radiocarbon age and eight OSL ages are used to assign ages to landforms.

Charcoal from the outwash plain east of the Brighton Fan was dated at > 46 ka 14C yrs

BP. Because the outwash plain was deposited proximal to a receding ice front it is

unlikely that the organics originated from vegetation growing near the glacier. Instead,

the charcoal was remobilized from older material up ice or eroded, transported and

deposited from pre Late-Wisconsinan sediments.

The radiocarbon chronology in the literature puts the Huron-Erie lobe margin in

the study area around 18.2 ka (Glover et al., 2011). 18.2 ka falls within the two-sigma

error of all four of the OSL ages collected from PRMC deposits which requires the

Huron-Erie Lobe’s ice margin to be nearby as it sourced the PRMC outwash. The OSL

ages also suggest that the Saginaw Lobe must have retreated from the study area before

18 ka (oldest overlap of PRMC OSL ages) and perhaps as early as 24 ka (oldest PRMC

OSL age) because space is needed for deposition of the Lima Plain sediment and

formation of the PRMC (Figure 3-1). From the available data and by not using the old

33.8 ± 7.4 ka or young 15.7 ± 2.7 and 17.1 ± 3.0 OSL ages for reasons discussed in

section 3.7, the remaining ages of 23.3 ± 5.8 and 23.4 ± 4.4 ka are the best constraints to

date the PRMC outwash to ~23 ka.

77

OSL ages on dunes record eolian activity between 12.5 and 10.5 the last period of

dune activity in the study area. The Mongo Dunes have previously been dated and two periods of activity for the Mongo Dunes have been suggested (Fisher et al., 2019). The dunes within the valley are aged ~14 ka and dunes on the surrounding uplands are aged between 9.5-12.5 ka (Fisher et al., 2019). Including uncertainties the dunes sampled in this thesis are from the valley floor and fall between 9 and 14 ka, however, actual ages are between 10.5 and 12.5 ka. Dune activity could have reached a peak during the

Younger Dryas 12.9 - 11.8 ka (Fisher et al., 2019). The radiocarbon and OSL ages discussed above will be applied to the and sedimentology to provide constraining ages on the deglaciation of the study area.

Figure 4-3: Deglacial OSL and radiocarbon ages between the Shipshewana Moraine and the Sturgis Moraine (Figure 1-5). OSL ages are from this study (IGWS) and Dzeikan (2017). Radiocarbon ages are from Horton (2015) and Dzeikan (2017). Modified from Fisher et al. (in prep).

78

4.4 Deglaciation

Deglaciation of the interlobate area between the Saginaw Lobe and Huron-Erie

Lobe is not a simple retreat of two neighboring ice lobes. Instead the landforms record

that the Saginaw Lobe and the Huron-Erie Lobe occupied the study area during the Late

Wisconsinan glaciation. Results from this thesis are compared with previous work and a

model for deglaciation is proposed.

What caused the Saginaw Lobe to retreat earlier that the Huron-Erie Lobe is

uncertain, but it may be attributed to the Saginaw Lobe’s thinness as it advanced over the central Michigan uplands (Leverett and Taylor, 1915; Patterson, 1997; Kehew, 2012). A

thin Saginaw Lobe would stagnate and retreat while the Huron-Erie Lobe stayed in the study area. A complementary explanation for early retreat could be a cessation of the ice supply to the Saginaw Lobe as ice preferentially streamed down the Huron Basin and

Michigan Basin.

During the glacial advance that deposited the Newbury Till (Nissourian Stade) the

Saginaw Lobe and the Huron-Erie Lobe covered the study area (Figure 4-4). The

Newbury Till is the uppermost preserved till of Wisconsinan age. The timing of the

Nissourian Stade correlates with early Woodfordian Drift and was deposited before 25 ka

(Fullerton 1986). During the Nissourian Stade incipient tunnel channels were eroded into and through the Newbury Till possibly while ice was at the Shipshewana margin (Figure

1-5). Eskers were deposited in tunnel channels at this time.

The two different orientations of tunnel channels that exist in the study area

(Figure 3-1) record either a shift in the preferred subglacial drainage pathway or two separate glacial advances. The esker in the parallel morphology tunnel channel crosscuts

79

Figure 4-4: Saginaw Lobe tunnel channels formed while ice covered the entire study area during the Nissourian Stade and before formation of the PRMC at ~23 ka.

the Ontario Channel suggesting that the N-S trending Ontario Channel is older than the

NE-SW trending parallel tunnel channel because preservation of the esker form during

erosion of the Ontario Channel is unlikely.

As final deglaciation occurred the first landform to develop in the study area is the

outwash plain (Figure 4-5). This outwash plain acts as a reference for the other

landforms as it is the oldest geomorphic surface in the study area.

The Huron-Erie Lobe remained at the ice position preserved by the Brighton Fan

(Figure 4-6). The location of the Saginaw Lobe at this time must be near the Sturgis

Moraine as the Brighton Fan was uninhibited by the Saginaw Lobe while forming.

Stagnant ice was still in the area and was able to preserve the morphology of tunnel

channels as it was buried by the Brighton Fan.

80

Figure 4-5: Deposition of outwash plain (op) during retreat of the Saginaw Lobe. Ice retreat and sediment deposition continued northward until Saginaw Lobe stabilized at the Sturgis Moraine. Deposition of outwash plain was before 23 ka. Ice margins are approximate.

Figure 4-6: Ice position during deposition of the Brighton Fan off the Huron-Erie Lobe. Arrows show actively forming fan. Deposition of Brighton Fan is before the formation of the PRMC at 23 ka. Ice margins are approximate.

81

After deposition of the Brighton Fan the Huron-Erie Lobe retreated northeastward and joined the Saginaw Lobe at the Sturgis Moraine (Figure 4-7). The Huron-Erie Lobe is responsible for the 2 km of the Sturgis Moraine south of the bend in the moraine near

Wall Lake (Figure 3-5). Outwash fans associated with the Sturgis Moraine are deposited at this time. The proximity of the ice lobes continues to preserve permafrost and prevent the buried stagnant ice from melting and the morphology of the tunnel channels is preserved.

Next, the Saginaw Lobe retreats northward out of the study area and the Huron-

Erie Lobe retreats eastward to the ice position recorded by the Turkey Creek and Flint

Fans (Figure 4-8). The Huron-Erie Lobe stayed at this position long enough to build the fans before releasing the meltwater that eroded the outwash fans and cut the PRMC.

Figure 4-7: Ice position during formation of the Sturgis Moraine and related fans (sf). Arrows show currently forming fan. Deposition of Sturgis Fans is before 23 ka. Ice margins are approximate.

82

Figure 4-8: Ice position during formation of the Flint Fan, Turkey Creek Fan (tcf) and PRMC (~23 ka). Arrows show currently forming fans that would be modified by the PRMC. Ice margins are approximate. Blue arrows show PRMC flow direction.

In some places the meltwater that formed the PRMC eroded through and removed

buried ice in tunnel channels of both N-S and NE-SW orientations. However, the deepest tunnel channel deposits and buried ice remained. OSL ages collected in this study suggest meltwater flowing through the PRMC became depositional at 23 ka and continued to

deposit material in the PRMC until 16 ka. Although the ice margin was further east by

16 ka (Fullerton, 1980; Glover et al., 2011) meltwater to mobilize material could still be

supplied by stagnant ice. Additionally, the sediment may still been easily mobilized by

rainfall and other processes until vegetation repopulated the area.

Organics from nearby lakes suggest that vegetation repopulation may have occurred as

late as 16 ka (Horton, 2015; Dzeikan 2017).

83

As the Saginaw Lobe retreated northward and the Huron-Erie Lobe retreated

eastward the temperature of the study area increased. Warmer temperatures melted

buried ice forming a linear pattern of depressions in the outwash plain, outwash fans and

PRMC deposits revealing the former pathways of tunnel channels (Figure 4-9). After

deglaciation dunes also formed and may have first stabilized at 14.2 ka (Fisher et al.,

2019) only for the dunes in the PRMC to be reactivated during the Younger Dryas before

stabilizing a final time.

Figure 4-9: Landforms used to reconstruct deglaciation after ice retreats from the area and buried ice begins to melt before the oldest radiocarbon from kettle lakes was deposited ~16.2 ka (Dzeikan, 2017).

84

4.5 Northern Indiana OSL.

From an OSL perspective, quartz grains from glacial fluvial sediment in northern

Indiana are poorly behaved. Less than 57% of grains showed luminescence strong enough to be measured. A number of grains were also unfit for OSL because of a significant slow component in the OSL signal. Approximately 10% of grains were saturated beyond capacity, also making them unfit for OSL. The samples analyzed for this project have behaved similar to other northern Indiana samples collected and analyzed at the Indiana Geological and Water Survey (IGWS) OSL Lab, and at the

Illinois State Geological Survey (ISGS) OSL Lab (Huot, 2017). A tally of rejected aliquots is shown in Table 4.1. Approximately 16% of grains were used for OSL calculations.

Table 4.1: Tally of rejected aliquots

IGWS- IGWS- IGWS- IGWS- IGWS- IGWS- IGWS- IGWS- Total 48 58 59 60 61 149 150 153 Total 144 100 110 177 159 120 154 40 1004 Aliquots Run Low or No 54 66 45 116 84 102 87 14 568 Signal Slow 23 0 1 13 30 0 14 0 81 component Saturated 16 16 1 9 28 1 16 0 87 Accepted 51 18 63 32 18 18 57 26 283 Aliquots >25% 20 9 11 11 3 5 9 1 69 Error >±10% 10 2 17 4 3 0 12 1 49 R5/N Recycling 19 3 4 3 3 5 2 1 40 >1+-.2 MAM 14 11 40 20 12 12 26 23 158 Aliquots

85

4.5 Conclusions

The goal of this thesis was to determine when the Saginaw Lobe retreated from

Indiana by testing the hypothesis that the Mongo area was ice free by 23 ka. Objectives met to test the hypothesis were: surficial mapping of the study area, creation of stratigraphic columns and cross sections, resolution of the crosscutting relationship of the tunnel channels and other landforms, and the use of radiocarbon and OSL dating methods to provide chronology on the landforms.

Surficial mapping found that there were two generations of tunnel channels. The older tunnel channels are north-south trending and younger tunnel channels are northeast- southwest trending. Ice filled tunnel channels were covered by outwash fans from the

Saginaw Lobe at the Sturgis Moraine and the Huron-Erie Lobe at three different ice margins. The meltwater flow that incised the PRMC originated from the Huron-Erie

Lobe and eroded older fans and scoured the outwash plain but did not erode deep enough to remove all of the buried ice in all of the tunnel channels. Stratigraphic columns created from sediment cores, well-logs, and GPR surveys revealed that the PRMC deposits were collapsed beneath surface depressions, providing evidence for buried stagnant ice preserving the palimpsest form of tunnel channels. Additionally, water well logs revealed that the thickness of surficial outwash deposits were between 5 m and 20 m.

OSL provided absolute dates on the uppermost outwash within the PRMC and Mongo dunes to reconstruct the deglacial chronology.

The OSL data is used to accept the hypothesis that the PRMC is ice free by 23 ka.

The hypothesis was supported by an oldest OSL age of 23 ka on subaerial glacial fluvial deposits in the PRMC. The Saginaw Lobe had to have retreated to the Sturgis Moraine

86

before the PRMC was cut and OSL dated outwash was deposited. However, buried,

stagnant ice within the tunnel channels did not melt until later.

4.6 Implications

This thesis builds on work of earlier University of Toledo graduate student

researchers Horton (2015) and Dzeikan (2017). Horton (2015) dated organics in kettle

lakes in the Sturgis Moraine at 16.9 ka. These radiocarbon ages for deglaciation of the

Sturgis Moraine are younger than OSL ages and can be attributed to a lag time between

the establishment of organics in the lakes and deglaciation. Dzeikan (2017) investigated

this lag time by dating organics and sediments in kettles on both the Sturgis Moraine and

the Shipshewana Moraine. Radiocarbon ages acquired from kettles were between 5000

and 7000 years younger than OSL acquired from sandy sediment beneath. OSL ages in

this study agree with 20.4 ka for the deglaciation of the Sturgis Moraine and 23.6 ka for

the deglaciation of the Shipshewana Moraine (Dzeikan, 2017)(Figure 4-1).

The study area mapped by Brown et al. (1998) was remapped and tunnel channels

were determined to be palimpsest features. Tunnel channels in the study area are features

of the Saginaw Lobe buried by Huron-Erie Lobe fans and younger Saginaw Lobe fans.

This suggests the Saginaw Lobe had retreated north to the Sturgis Moraine or stagnated in place and thicker ice in tunnel channels was preserved. The PRMC was dated using

OSL and provides chronology controls for the Saginaw Lobe. The OSL ages on the

PRMC join other OSL ages collected in Indiana and Michigan (Dzeikan 2017, Kehew et al., 2017 and Schaetzl et al., 2017) that suggest ice retreat had occurred earlier than radiocarbon ages suggest.

87

4.7 Future Work

The use of OSL in glacial fluvial deposits has been limited, in part because

difficulties that exist due to the incomplete or partial bleaching of sediment, which

requires a large number of aliquots to be processed. The advantage OSL provides over

other techniques such as radiocarbon is it directly dates the deposition of sediment rather

than providing ages on vegetation colonization. However, OSL dating has larger errors than radiocarbon dating.

In this study 11 samples were collected and prepped for OSL but only eight had aliquots measured for OSL. Additional OSL ages on the PRMC fill would provide a

more accurate age of PRMC sediment deposition and test if there were multiple

meltwater events through the PRMC. Additional aliquots can be run on OSL ages with a

small accepted grain count to lessen the effect of outliers on age calculation and

determine a more precise age. Additionally, the small aliquot method of OSL could be

tested by running samples used in this study through a single aliquot machine and

comparing ages. OSL can also be extended to other subaerial glacial fluvial deposits in

the study area such as outwash fans.

Additionally, deep coring techniques (i.e. rotosonic) and deep such as

seismic reflection could resolve the depth of the PRMC and faulting in tunnel channels to

test the conclusions of this study. These more advanced techniques would further resolve

the subsurface structure of these landforms. A better understanding of geometry of the

subsurface would also be useful for the characterization of shallow and

determining their potential as a groundwater resource.

88

References

Aitken, M. J., 1998, An Introduction to Optical Dating: , Oxford University Press, 267 p.

Annan, A. P., 2009, Electromagnetic Principles of Ground Penetrating Radar, in Jol, H. M., ed., Ground penetrating radar theory and applications: Amsterdam, Elsevier Science, 509 p.

Antinao-Rojas, J. L., 2019, personal communication, IGWS-1 (Voyles 6) dose recovery results after 300s on 20 discs.

Arbogast, A. F., Scull, P., Schaetzl, R., Harrison, J., Jameson, T. P., and Crozier, S., 1997, Concurrent stabilization of some interior dune fields in Michigan: , v. 18, p. 63-79.

Bennett, M. R., and Glasser, N. F., 2009, Glacial Geology: Ice Sheets and Landforms, Wiley-Blackwell, 385 p.

Blewett, W. L., Winters, H. A., and Rieck, R. L., 1993, New age control on the Port Huron moraine in northern Michigan: Physical Geography v. 14, no. 2, p. 131 -138.

Bridge, J. S., 2009, Advances in Fluvial Sedimentology using GPR, in Jol, H. M., ed., Ground penetrating radar theory and applications: Amserdam, Elsevier Sceince, 509 p.

Bristow, C. S., 2009, Ground penetrating radar in aeolian dune , in Jol, H. M., ed., Ground penetrating radar theory and applications: Amsterdam, Elsevier Science, p. 509.

89

Brodzikowski, K., and Van Loon, A. J., 1987, A Systematic Classification of Glacial and Periglacial Environments, Facies and Deposits: Earth –Science Reviews, v. 24, p. 297-381.

Broecker, W. S., and Farrand, W. R., 1963, Radiocarbon age of the Two Creeks forest bed, Wisconsin: Geological Society of America Bulletin, v. 74, p. 795-802.

Brown, S. E., 1999, Ice Marginal Environments of Huron-Erie and Saginaw Lobes, North Central Indiana Midwest Friends of the Field Conference, v. 45: Goshen, Indiana, Indiana Geological Survey, p. 25-38.

Brown, S. E., Fleming, A. H., Jones, H., and Schrader, T. L., 1998, Glacial Terrains of the Mongo, Wolcottville, and the Indiana part of the Burr Oak 7.5-Minute Quadrangles, LaGrange and Noble Counties, Indiana; Indiana Geological Survey, Map 98-6: Bloomington, Indiana.

Brown, S.E., and Jones, H., 1999a, Glacial Terrains of the Orland and Indiana Part of the Bronson South 7.5-minute Quadrangles: Indiana Geological Survey, Map: Bloomington, Indiana.

Brown, S.E., and Jones, H., 1999b, Glacial Terrains of the Stroh 7.5-minute Quadrangle: Indiana Geological Survey, Map: Bloomington, Indiana.

Burgis, W. A., 1970, The Imlay outlet of glacial lake Maumee, Imlay City, Michigan M.S. Thesis: University of Michigan.

Burgis, W. A., 1977, Late-Wisconsinan history of northeastern Lower Michigan PhD Dissertation: University of Michigan.

Campbell, M. C., Fisher, T. G., and Goble, R. J., 2011, Terrestrial sensitivity to abrupt cooling recorded by aeolian activity in northwest Ohio, USA: Quaternary Research, v. 75, p. 411-416.

Clayton, L., Attig, J. W., Nelson, R. H., Johnson, M. D., Jennings, C. E., Syverson, K. M., 2008, Ice-walled-lake plains: Implications for the origin of hummocky glacial topography in middle : Geomorphology, v.97, p. 237-248.

Clayton, L., Attig, J. W., and Mickelson, D. M., 1999, Tunnel channels formed in Wisconsin during the last glaciation: Geological Society of America Special Paper, no. 337, p. 69-74.

Colgan, P. M., Amidon, W. H., and Thurkettle, S. A., 2017, Inland dunes on the abandoned bed of Glacial Lake indicate eolian activity during the Pleistocene-Holocene transition, southwestern Michigan, USA: Quaternary Research, v.87, no. 01, p. 66-81.

90

Colgan, P. M., Mickelson, D. M., and Cutler, P. M., 2003, Ice-Marginal Terrestrial Landsystems: Southern Margin, in Evans, D. J. A., ed., Glacial Land Systems: London, Journal of , 532 p.

Curry, B. B., Hajic, E. R., Clark, J. A., Befus, K. M., Carrell, J. E., and Brown, S. E., 2014, The Kankakee Torrent and other large meltwater flooding events during the last deglaciation, Illinois, USA: Quaternary Science Reviews, v. 90, p. 22-36.

Curry, B. B., Lowell, T. V., Wang, H., Anderson, A. C., 2018, Revised time-distance diagram for the Lake Michigan Lobe, Michigan Subepisode, Wisconsin Episode, Illinois, USA, The Geological Society of America Special Paper 530, p 69-101.

Duller, G. A. T., 2006, Single grain optical dating of glacigenic deposits: Quaternary Geochronology, v. 1, p. 296-304.

Durcan, J.A., King, G.E., Duller, G.A.T., 2015, DRAC: Dose Rate and Age Calculator for trapped charge dating, Quaternary Geochronology, v. 28, p. 54-61

Dworkin, S. I., Larson, G. J., and Monaghan, G. W., 1985, Late Wisconsinan ice-flow reconstruction for the central Great Lakes region: Canadian Journal of Earth Sciences, v. 22, p. 935-940.

Dyke, A. S., 2004, An outline of North American Deglaciation with emphasis on central and northern Canada: Quaternary glaciations: Extent and chronology, v. 2, p. 373. 28.

Dziekan, M. R., 2017, Origins of Basal Sediment within Kettle Lakes in Southern Michigan and Northern Indiana M.S. Thesis: University of Toledo, 136 p.

Eyles, N., Boyce, J. I., Barendregt, R. W., 1999, Hummocky moraine: sedimentary record of stagnant Laurentide Ice Sheet lobes resting on soft beds: Sedimentary Geology, v 123, p. 163-174.

Fisher, T. G., Blockland, J. D., Anderson, B., Krantz, D. E., Stierman, D. J., and Goble, R., 2015, Evidence of Sequence and Age of Ancestral Lake Erie Lake-Levels, Northwest Ohio: Ohio Journal of Science, v. 115, no. 2, p. 61-77.

Fisher, T. G., Dziekan, M. R., Horton, J., Lepper, K., Curry, B. B., McCarthy, F., Loope, H. M., in prep, Deglacial Chronology of the Sturgis Moraine and southern Great Lakes deglacial radiocarbon lags.

Fisher, T. G., Horton, J., Lepper, K., Loope, H., 2019, Aeolian activity during Late Glacial time, with an example from Mongo, Indiana, USA: Canadian Journal of , v. 56, p. 175-182.

91

Fisher, T. G., Jol, H. M., and Boudreau, A. M., 2005, Saginaw Lobe tunnel channels (Laurentide Ice Sheet) and their significance in south-central Michigan, USA: Quaternary Science Reviews, v. 24, no. 22, p. 2375-2391.

Fisher, T. G., and Taylor, L. D., 2002, Sedimentary and stratigraphic evidence for subglacial flooding, south-central Michigan, USA: Quaternary International, v. 90, p. 87-115.

Fleming, A. H., 1998, Atlas of hydrogeologic settings of LaGrange County, Indiana: Indiana Geological Survey.

Fleming, A. H., Brown, S. E., Smous, A. J., and Schrader, T. L., 1997, Glacial terrains off the Topeka, Shipshewana, Oliver Lake, Lagrange and Sturgis 7.5-minute quadrangles, in Survey, I. G., and University, W. M., eds.

Fullerton, D. S., 1980, Preliminary Correlation of Post-Erie Interstadial Events (16,000 10,000 Radiocarbon Years Before Present), Central and Eastern Great Lakes Region, and Hudson, Champlain, and St. Lawrence Lowlands, United States and Canada: Geological Survey Professional Paper, v. 1089, 57 p.

Fullerton, D.S., 1986, Stratigraphy and Correlation of Glacial Deposits from Indiana to New York and New Jersey: Quaternary Science Reviews, Quaternary Glaciations in the Northern Hemisphere, v. 5, p. 23-37.

Fullerton D. S., and Richmond, G. M., 1991, Quaternary Geologic Map of the Lake Erie 4° x 6° Quadrangle, United States and Canada: Quaternary Geologic Atlas of the United States, U.S. Geological Survey: Map I-1420 (NK 17).

Galbraith, R. F., Roberts, R. G., Laslett, G. M., Yoshida, H., and Olley, J. M., 1999, Optical Dating of Single and Multiple Grains of Quartz from Jinmium Rock Shelter, Northern Australia: Part I, Experimental Design and Statistical Models: Archaeometry, v. 41, no. 2, p. 339-364.

Glover, K. C., Lowell, T. V., Wiles, G. C., Pair, D., Applegate, P., and Hajdas, I., 2011, Deglaciation, basin formation and post-glacial climate change from a regional network of sediment core sites in Ohio and eastern Indiana: Quaternary Research, v. 76, p. 401-410.

Gravenor, C.P., and Kupsch, W.Q., 1959, Ice-disintegration features in western Canada: Journal of Geology, v. 67, p. 48–64.

Gravenor, C. P., and Stupavsky, M., 1976, Magnetic, physical, and lithologic properties and age of till exposed along the east of Lake Huron, Ontario: Canada Journal of Earth Science, v. 13, p. 1655 - 1666.

92

Gray, H. H., 1989, Quaternary geologic map of Indiana: Indiana Geolgocial Survey, Miscellaneous Map 49.

Horton, J. M., 2015, The Deglacial Chronology of the Sturgis Moraine in South-Central Michigan and Northeast Indiana M.S. Thesis: University of Toledo, 100 p.

Howard, J. L., 2010, Late Pleistocene glaciolacustrine sedimentation and paleogeography of southeastern Michigan, USA: Sedimentary Geology, v. 223, p. 126-142.

Huot, S., 2017, unpublished, Luminescence dating report for William Monaghan, from the Indiana Geological Survey: Prairie Research Institute, Illinois State Geological Survey, 22 p.

Johnson, M.D., Clayton, L., 2003, Supraglacial landsystems in lowland terrain, in Evans, D. J. A. (Ed.), Glacial Landsystems: Arnold, London, p., 228–258.

Jol, H. M., 2009, Ground Penetrating Radar Theory and Applications, Amsterdam, Elsevier Science. 544 p.

Karaffa, M.D. and Sowder, K.H., 2010, Surficial geology of LaGrange County – Digital Compilation: Indiana Geological Survey, Miscellaneous Map 79, scale 1:48,000.

Kehew, A. E., Beukema, S. P., Bird, B. C., and Kozlowski, A. L., 2005, Fast flow of the Lake Michigan Lobe: evidence from sediment-landform assemblages in southwestern Michigan, USA: Quaternary Science Reviews, v. 24, p. 2335-2353.

Kehew, A. E., Esch, J., M., Curry, B. B., Huot, S., Yellich, J. A., and Karki, S., 2017, Meltwater Source for the Kankakee Torrent, GSA Annual Meeting: Seattle, Washington, USA, The Geological Society of America.

Kehew, A. E., Esch, J., M., Kozlowski, A. L., and Ewald, S. K., 2012, Glacial landsystems and dynamics of the Saginaw Lobe of the Laurentide Ice Sheet, Michigan, USA: Quaternary International, v. 260, p. 21-31.

Kehew, A. E., Ewald, S. K., Esch, J. M., Kozlowski, A. L., 2013, On the origin of tunnel valleys of the Saginaw Lobe of the Laurentide Ice Sheet; Michigan, USA. Boreas, Vol. 42, pp. 442–462.

Kehew, A. E., and Kozlowski, A. L., 2007, Tunnel Channels of the Saginaw Lobe, Michigan, USA: Geological Survey of Finland, Special Paper, v. 46, p. 69-78.

Kehew, A. E., Nicks, L. P., and Straw, W. T., 1999, Palimpsest tunnel valleys: evidence for relative timing of advances in an interlobate area of the Laurentide ice sheet: Annals of , v. 28, p. 47-52.

93

Kilibarda, Z., and Blockland, J., 2011, Morphology and origin of the Fair Oaks Dunes in NW Indiana, USA: Geomorphology, v. 125, no. 2, p. 305-318.

Kozlowski, A.L., 1999. Three Dimensional mapping of the east Leroy and Union City 7.5 minute Quadrangles I southwest Michigan. Unpublished M.S. Thesis, Western Michigan University.

Kozlowski, A.L., 2004. Origin of the Central valley, Southwestern Michigan, USA. Unpublished Ph.D. Dissertation, Western Michigan University, USA.

Kozlowski, A.L., Kehew, A.E., Bird, B.C., 2003. Tunnel channels of the Saginaw Lobe, southern Michigan. Proceedings of the 34th Binghamton Geomorphology Symposium, October 3–5, 2003, Binghamton, USA.

Krüger, J., 1997, Development of minor outwash fans at Kötlujökull, . Quaternary Science Reviews, v. 16, p. 649–659.

Larson, G. J., Lowell, T. V., and Ostrum, N. E., 1994, Evidence for the Two Creeks interstade in the Lake Huron basin: Canada Journal of Earth Science, v. 31, p. 793-797.

Larson, G. J., and Schaetzl, R., 2001, Origin and Evolution of the Great Lakes: Journal of Great Lakes Research, v. 27, no. 4, p. 518-546.

Leverett, F., and Taylor, F. B., 1915, The Pleistocene of Indiana and Michigan and the History of the Great Lakes, in Interior, D. o. t., ed., Monographs of the United States Geological Survey Volume 53: Washington, 527 p.

Loope, H. M., Antinao-Rojas, J. L., Monaghan, G., Autio, R. J., Curry, B. B., Grimely, D. A., Huot, S., Lowell, T. V., Nash, T. A., 2018, At the edge of the laurentide ice sheet: Stratigraphy and chronology of glacial deposits in central Indiana. Field Guide abstract.

Lowell, T. V., and Denton, G. H., 1999, Role of climate oscillations in determining ice margin position: Hypothesis, examples, and implications: Geological Society of America Special Paper, v. 337, p. 193-203.

Miall, A. D., 1977, A Review of the Braided-River Depositional Environment: Earth Science Reviews, v. 13, p. 1-62.

Mickelson, D. M., Clayton, L., Fullerton, D. S., and Borns, H. W. J., 1983, The Late Wisconsin glacial record of the Laurentide ice sheet in the United States, in Wright, H. E., and Porter, S. C., eds., Late-Quaternary Environments of the United States: The Late Pleistocene, Volume 1, University of Press, 298 p.

94

Monaghan, G. W., and Larson, G. J., 1986, Late Wisconsinan drift stratigraphy of the Saginaw Ice Lobe in south-central Michigan: GSA Bulletin, v. 97, no. 3, p. 324 -328.

Murray, A. S., Wintle, A. G., 2003, The single aliquot regenerative dose protocol: potential for improvements in reliability: Radiation Measurements v. 37, p. 377- 381.

Ogden, J. G., and Hay, R. J., 1973, Ohio Wesleyan University Natural Radiocarbon Measurements V: Radiocarbon, v. 15, no. 2, p. 350-366.

Patterson, C.J., 1997. Southern Laurentide ice lobes were created by ice streams: Des Moines Lobe in Minnesota, USA. Sedimentary Geology v. 111, p. 249–261.

Peterson, G., Johnson, M. D., Dahlgren, S., Påsse, T., Alexanderson, H., 2018, Genesis of hummocks found in tunnel valleys: an example from Hörda, southern Sweden: GFF, p. 1-13.

Piotrowski, J. A., 1994, Tunnel-valley formation in northwest Germany—geology, mechanisms of formation and subglacial bed conditions for the Bornhöved tunnel valley: Sedimentary Geology, v. 89, p. 107-141.

Rech, J. A., Nekola, J. C., Pigati, J. S., 2012, Radiocarbon ages of terrestrial gastropods extend duration of ice-free conditions at the Two Creeks forest bed, Wisconsin, USA: Quaternary Research, v. 77 p. 289-292.

Rhodes, E. J., 2011, Optically Stimulated Luminescence Dating of Sediments over the Past 200,000 Years: Annual Review of Earth and Planetary Science, v. 39, p. 461 -488.

Richmond, G. M., and Fullerton, D. S., 1983, Quaternary Geologic Map of the Chicago 4° x 6° Quadrangle, United States: Quaternary Geologic Atlas of the United States, U. S. Geological Survey, Map, I-1420 (NK-16).

Richmond, G. M., and Fullerton, D. S., 1984, Quaternary Geologic Map of the 4° x 6° Quadrangle, United States: Quaternary Geologic Atlas of the United States, U. S. Geological Survey, Map, I-1420 (NK-16).

Rust, B.R. and Romanelli, R., 1975, Late Quaternary subaqueous outwash deposits near Ottawa, Canada. In: A.V. Jopling and B.C. McDonald (Eds.), Glaciofluvial and Glaciolacustrine Sedimentation. Soc. Econ. Paleontol. Mineral., Spec. Publ., v. 23, p. 177-192.

Schaetzl, R. J., 2001, Late Pleistocene ice flow directions and the age of glacial landscapes in northern lower Michigan: Physical Geography, v. 22, p. 28-41.

95

Schaetzl, R. J., Lepper, K., Thomas, S. E., Grove, L., Treiber, E., Farmer, A., Fillmore, A., Lee, J., Dickerson, B., and Alme, K., 2017, Kame deltas provide evidence for a new glacial lake and suggest early glacial retreat from central Lower Michigan, USA: Geomorphology, v. 280, p. 167-178.

Shreve, R. L., 1972, Movement of Water in Glacier: Journal of Glaciology, v. 11, no. 62, p. 205-214

Shreve, R. L., 1985, Esker characteristics in terms of glacier physics, Katahdin esker system, Maine: Geological Society of America Bulletin, v. 96, p. 639-646

Siegenthaler, C., and Huggenberger, P., 1993, Pleistocene Rhine gravel; Deposits of a braided river system with dominant pool preservation: In Best, J. L., and Bristow, C. S. (eds), 1993, Braided Rivers, Geological Society Special Publication No. 75, p. 147-162.

Sjogren, D. B., Fisher, T. G., Taylor, L. D., Jol, H. M., Munro-Stasiuk, M. J., 2002, Incipient tunnel channels: Quaternary International, v. 90, p. 41-56.

Stalker, A.M., 1960. Ice-pressed drift forms and associated deposits in Alberta. Geological Survey of Canada Bulletin 57, 38 pp.

Wintle, A. G., and Adamiec, G., 2017, Optically stimulated luminescence signals from quartz: A review: Radiation Measurements, v. 98, p. 10-33.

Zumberge, J. H., 1960, Correlation of Wisconsin Drifts in Illinois, Indiana, Michigan, and Ohio: Bulletin of the Geological Society of America, v. 71, p. 1177-1188.

96

Appendix A

Ground Penetrating Radar

Figure A-1: Results of a common midpoint survey of the PRMC deposits. A velocity of 0.07 m/ns was used when processing GPR transects.

97

Figure A-2: GPR transect PR-01 with interpretations. Transect crosses a dune in the Mongo Dune Field see Figure 3-15 for transect location.

98

Figure A-3: GPR transect PR-03 with interpretations. Transect crosses a dune in the Mongo Dune Field see Figure 3-15 for transect location.

99

Figure A-4: GPR transect PR-05 with interpretations. Transect on PRMC see Figure 3-15 for transect location.

100

Figure A-5: GPR transect PR-10 with interpretations. Transect on PRMC see Figure 3-15 for transect location.

101

Figure A-6: GPR transect PR-11 with interpretations. Transect on Ontario Channel see Figure 3-15 for transect location.

102

Figure A-7: GPR transect PR-12 with interpretations. Transect on outwash plain see Figure 3-15 for transect location.

103

Figure A-8: GPR transect PR-18 with interpretations. Transect on Brighton Fan see Figure 3-15 for transect location.

104

Figure A-9: GPR transect PR-19 with interpretations. Transect on kettle depression see Figure 3-15 for transect location.

105

Appendix B

Optically Stimulated Luminescence

Table B.1: Measured dosimetrically significant element analysis.

OSL Sample Dose Rate ID Rb (ppm) Th (ppm) U (ppm) K (ppm) 132 27.7 2.58 1.36 0.70 IGWS 48 133 34.5 5.51 1.59 0.86 148 33.5 2.02 1.76 1.01 IGWS 58 149 27.9 1.76 1.57 0.87 150 31.7 1.96 0.72 1.01 IGWS 59 151 28.6 1.48 0.57 0.86 152 33.6 2.1 1.15 1.02 IGWS 60 153 34.5 2.72 1.73 1.04 154 25.5 2.46 1.58 0.81 IGWS 61 155 27.7 2.62 1.79 0.77 370 41.9 3.44 1.17 1.30 IGWS 149 371 35.2 2.46 0.69 1.14 372 25.9 2.81 0.99 0.86 IGWS 150 373 30 1.91 0.8 0.90 376 34.7 1.92 0.53 1.10 IGWS 153 377 38.6 2.56 0.95 1.20

106

Table B.2: Aliquots used in luminescence age calculation for IGWS-48. The following parameters were taken into consideration when choosing aliquots for age calculation: (1) Error < 25% of the measured age, (2) Recycling Ratio between 0.8 and 1.2, (3) Recuperation between -10% and +10%.

Filename Disc# Equivalent Dose (Gy) Recycling Ratio Recuperation (%) IGWS-48-M2 9 61.17 ± 15.49 0.81 ± 0.23 -0.32 ± 5.41 IGWS-48-M3 6 78.39 ± 14.70 1.08 ± 0.24 1.16 ± 4.28 IGWS-48-M3 13 99.68 ± 22.50 0.93 ± 0.53 4.95 ± 10.91 IGWS-48-M3 21 170.22 ± 23.23 0.93 ± 0.15 -1.45 ± 1.34 IGWS-48-M5 3 74.35 ± 14.11 1.05 ± 0.18 3.12 ± 2.85 IGWS-48-M5 9 46.33 ± 6.37 0.84 ± 0.15 -1.23 ± 3.77 IGWS-48-M5 33 46.10 ± 6.43 0.94 ± 0.12 0.09 ± 0.55 IGWS-48-M6 12 55.81 ± 9.50 0.93 ± 0.14 -2.12 ± 2.37 IGWS-48-M6 14 67.30 ± 11.84 0.96 ± 0.22 -4.16 ± 7.55 IGWS-48-M6 26 54.81 ± 7.83 0.93 ± 0.16 -2.57 ± 5.25 IGWS-48-M6 30 33.25 ± 6.85 0.86 ± 0.15 -1.09 ± 4.68 IGWS-48-M6 31 79.80 ± 12.45 0.83 ± 0.15 1.60 ± 2.91 IGWS-48-M3 14 30.31 ± 5.21 1.01 ± 0.18 5.55 ± 9.34 IGWS-48-M6 32 185.82 ± 41.19 1.06 ± 0.21 7.15 ± 3.12

Figure B-1: Radial plot for IGWS-48. Minimum age model used for age calculation.

107

Table B.3: Aliquots used in luminescence age calculation for IGWS-58. The following parameters were taken into consideration when choosing aliquots for age calculation: (1) Error < 25% of the measured age, (2) Recycling Ratio between 0.8 and 1.2, (3) Recuperation between -10% and +10%.

Filename Disc# Equivalent Dose (Gy) Recycling Ratio Recuperation (%) IGWS-58-M1 3 40.84 ± 10.40 1.01 ± 0.12 0.00 ± 0.04 IGWS-58-M1 9 50.05 ± 10.30 0.95 ± 0.20 3.10 ± 5.31 IGWS-58-M1 15 61.12 ± 12.22 0.78 ± 0.14 -8.76 ± 6.04 IGWS-58-M1 19 129.96 ± 33.49 0.99 ± 0.15 0.98 ± 1.42 IGWS-58-M2 9 99.76 ± 15.34 0.96 ± 0.15 0.57 ± 1.49 IGWS-58-M2 16 53.43 ± 11.45 0.88 ± 0.11 -0.46 ± 0.34 IGWS-58-M2 18 163.15 ± 37.31 0.87 ± 0.14 -0.86 ± 1.49 IGWS-58-M2 20 75.32 ± 15.56 0.79 ± 0.13 5.09 ± 2.17 IGWS-58-M2 21 214.37 ± 36.50 0.98 ± 0.17 -3.09 ± 1.75 IGWS-58-M3 11 39.82 ± 5.90 0.99 ± 0.15 -1.16 ± 2.88 IGWS-58-M3 34 56.18 ± 16.23 1.01 ± 0.22 -0.12 ± 6.55

Figure B-2: Radial plot for IGWS-58. Minimum age model used for age calculation

108

Table B.4: Aliquots used in luminescence age calculation for IGWS-59. The following parameters were taken into consideration when choosing aliquots for age calculation: (1) Error < 25% of the measured age, (2) Recycling Ratio between 0.8 and 1.2, (3) Recuperation between -10% and +10%.

Filename Disc# Equivalent Dose (Gy) Recycling Ratio Recuperation (%) IGWS-59-M1 3 34.76 ± 5.63 0.81 ± 0.10 0.32 ± 0.75 IGWS-59-M1 4 22.80 ± 3.95 0.85 ± 0.11 -1.36 ± 2.27 IGWS-59-M1 5 19.82 ± 2.12 1.03 ± 0.13 1.63 ± 0.55 IGWS-59-M1 8 20.70 ± 1.96 1.00 ± 0.12 0.89 ± 0.36 IGWS-59-M1 15 29.60 ± 4.57 0.90 ± 0.11 -0.77 ± 0.48 IGWS-59-M1 19 18.75 ± 1.99 0.92 ± 0.11 -0.39 ± 0.24 IGWS-59-M1 24 19.14 ± 2.51 0.95 ± 0.12 -0.99 ± 0.52 IGWS-59-M3 4 18.53 ± 2.03 0.84 ± 0.11 0.28 ± 0.80 IGWS-59-M3 10 18.57 ± 3.01 0.94 ± 0.11 0.20 ± 0.19 IGWS-59-M3 16 10.16 ± 1.98 0.87 ± 0.14 -0.95 ± 4.04 IGWS-59-M3 20 17.97 ± 3.48 0.89 ± 0.14 -0.75 ± 2.37 IGWS-59-M3 21 23.25 ± 2.73 0.87 ± 0.11 -0.36 ± 0.29 IGWS-59-M3 22 19.77 ± 2.48 0.92 ± 0.13 -2.78 ± 1.62 IGWS-59-M3 24 25.26 ± 6.22 1.02 ± 0.19 -0.67 ± 3.34 IGWS-59-M3 25 21.62 ± 2.86 1.03 ± 0.13 -1.56 ± 0.70 IGWS-59-M3 26 21.31 ± 2.97 0.80 ± 0.10 0.04 ± 0.46 IGWS-59-M3 27 11.29 ± 1.28 0.89 ± 0.12 -1.11 ± 2.56 IGWS-59-M2 3 21.40 ± 2.55 1.04 ± 0.16 3.18 ± 2.51 IGWS-59-M2 5 30.90 ± 6.48 0.81 ± 0.10 -0.16 ± 0.43 IGWS-59-M2 8 16.00 ± 3.40 0.81 ± 0.10 -0.29 ± 0.78 IGWS-59-M2 9 19.82 ± 2.16 0.90 ± 0.11 0.64 ± 0.22 IGWS-59-M2 10 14.51 ± 3.09 0.95 ± 0.21 -3.67 ± 6.81 IGWS-59-M2 11 21.60 ± 4.05 1.10 ± 0.19 0.11 ± 2.90 IGWS-59-M2 13 13.57 ± 1.39 0.97 ± 0.12 1.83 ± 1.01 IGWS-59-M2 17 10.63 ± 2.53 0.87 ± 0.14 0.11 ± 3.92 IGWS-59-M2 19 11.70 ± 1.70 0.80 ± 0.13 0.56 ± 4.98 IGWS-59-M2 20 20.27 ± 2.98 0.87 ± 0.11 -0.46 ± 0.41 IGWS-59-M2 21 27.09 ± 3.54 0.82 ± 0.11 -1.07 ± 0.98 IGWS-59-M2 23 18.81 ± 2.67 0.91 ± 0.13 -1.71 ± 2.11 IGWS-59-M2 24 45.018 ± 8.37 0.88 ± 0.20 0.98 ± 2.09 IGWS-59-M2 25 17.69 ± 3.05 0.84 ± 0.12 -0.16 ± 2.35 IGWS-59-M2 26 12.86 ± 1.50 0.90 ± 0.11 0.02 ± 0.20 IGWS-59-M2 27 16.29 ± 2.18 0.85 ± 0.11 -1.83 ± 1.51 IGWS-59-M2 28 21.39 ± 3.88 0.95 ± 0.14 -2.14 ± 1.95 IGWS-59-M2 29 15.01 ± 3.44 1.01 ± 0.19 -5.27 ± 4.66 IGWS-59-M2 30 5.79 ± 5.91 1.09 ± 0.25 2.17 ± 17.31

109

IGWS-59-M2 31 15.14 ± 2.17 0.96 ± 0.12 -0.01 ± 0.12 IGWS-59-M2 35 31.74 ± 4.47 0.91 ± 0.13 -0.13 ± 1.03 IGWS-59-M2 36 13.57 ± 2.52 0.97 ± 0.17 -2.91 ± 4.99 IGWS-59-M2 39 12.72 ± 2.71 1.26 ± 0.23 -6.09 ± 5.89

Figure B-3: Radial plot for IGWS-59. Minimum age model used for age calculation.

110

Table B.5: Aliquots used in luminescence age calculation for IGWS-60. The following parameters were taken into consideration when choosing aliquots for age calculation: (1) Error < 25% of the measured age, (2) Recycling Ratio between 0.8 and 1.2, (3) Recuperation between -10% and +10%.

Filename Disc# Equivalent Dose (Gy) Recycling Ratio Recuperation (%) IGWS-60-M1 17 50.40 ± 11.17 0.87 ± 0.12 -0.48 ± 1.42 IGWS-60-M1 21 22.87 ± 5.58 0.90 ± 0.17 -1.81 ± 7.32 IGWS-60-M1 32 53.24 ± 5.19 1.17 ± 0.16 -0.18 ± 1.63 IGWS-60-M1 35 10.12 ± 1.73 0.94 ± 0.14 -0.98 ± 3.29 IGWS-60-M1 37 33.88 ± 5.60 1.04 ± 0.15 3.49 ± 2.46 IGWS-60-M1 39 30.31 ± 3.64 1.12 ± 0.14 0.87 ± 0.62 IGWS-60-M2 22 34.05 ± 3.22 1.00 ± 0.12 -0.34 ± 0.64 IGWS-60-M2 26 51.93 ± 5.42 1.01 ± 0.12 0.10 ± 0.23 IGWS-60-M3 8 53.39 ± 9.85 0.96 ± 0.16 -7.10 ± 2.66 IGWS-60-M3 9 40.95 ± 7.26 0.93 ± 0.11 0.07 ± 0.25 IGWS-60-M3 28 33.69 ± 8.15 1.12 ± 0.18 -7.42 ± 3.97 IGWS-60-M4 1 50.32 ± 7.77 1.12 ± 0.16 -0.67 ± 1.60 IGWS-60-M4 11 34.38± 4.04 0.95 ± 0.12 -0.13 ± 0.17 IGWS-60-M4 26 30.21 ± 5.39 1.02 ± 0.14 -1.50 ± 1.86 IGWS-60-M7 4 35.78 ± 5.70 0.81 ± 0.11 1.77 ± 1.22 IGWS-60-M7 7 22.08 ± 3.07 1.00 ± 0.15 -2.47 ± 3.55 IGWS-60-M7 15 32.83 ± 7.44 0.85 ± 0.10 0.07 ± 0.13 IGWS-60-M7 19 18.66 ± 3.28 0.82 ± 0.12 2.23 ± 3.21 IGWS-60-M7 21 35.75 ± 8.15 0.99 ± 0.21 3.48 ± 8.79 IGWS-60-M7 31 30.93± 3.68 1.01 ± 0.13 2.79 ± 1.32

111

Figure B-4: Radial plot for IGWS-60. Minimum age model used for age calculation.

112

Table B.6: Aliquots used in luminescence age calculation for IGWS-61. The following parameters were taken into consideration when choosing aliquots for age calculation: (1) Error < 25% of the measured age, (2) Recycling Ratio between 0.8 and 1.2, (3) Recuperation between -10% and +10%.

Filename Disc# Equivalent Dose (Gy) Recycling Ratio Recuperation (%) IGWS-61-M2 40 26.93 ± 4.88 0.92 ± 0.13 -4.79 ± 2.37 IGWS-61-M3 6 101.61 ± 17.36 1.14 ± 0.45 -3.40 ± 6.70 IGWS-61-M3 8 61.03 ± 15.10 0.89 ± 0.11 -0.16 ± 0.26 IGWS-61-M3 9 53.31 ± 7.05 0.97 ± 0.12 -0.52 ± 0.42 IGWS-61-M3 15 25.27 ± 2.97 1.00 ± 0.14 7.35 ± 4.22 IGWS-61-M4 28 48.14 ± 7.19 1.18 ± 0.44 -2.79 ± 8.15 IGWS-61-M4 31 42.98 ± 4.95 0.94 ± 0.12 -0.97 ± 0.82 IGWS-61-M5 14 29.46 ± 2.89 1.13 ± 0.17 -3.34 ± 4.20 IGWS-61-M5 39 68.73 ± 8.95 0.96 ± 0.13 -1.15 ±0.91 IGWS-61-MS1 16 32.20 ± 5.67 0.86 ± 0.13 -0.02 ± 2.80 IGWS-61-MS1 18 45.47 ± 6.11 0.95 ± 0.16 -4.32 ± 3.40 IGWS-61-MS1 24 36.63 ± 3.78 0.92 ± 0.12 0.18 ± 1.00

Figure B-5: Radial plot for IGWS-61. Minimum age model used for age calculation.

113

Table B.7: Aliquots used in luminescence age calculation for IGWS-149. The following parameters were taken into consideration when choosing aliquots for age calculation: (1) Error < 25% of the measured age, (2) Recycling Ratio between 0.8 and 1.2, (3) Recuperation between -10% and +10%.

Filename Disc# Equivalent Dose (Gy) Recycling Ratio Recuperation (%) IGWS-149-M1 4 15.71 ± 1.78 0.92 ± 0.12 1.65 ± 2.12 IGWS-149-M1 6 23.58 ± 3.39 0.90 ± 0.13 2.23 ± 1.85 IGWS-149-M1 34 9.25 ± 2.27 0.95 ± 0.16 -4.01 ± 6.44 IGWS-149-M2 17 12.43 ± 2.80 1.03 ± 0.18 1.63 ± 4.91 IGWS-149-M2 18 13.34 ± 1.44 0.99 ± 0.12 0.30 ± 0.69 IGWS-149-M2 38 17.39 ± 3.86 0.89 ± 0.16 0.29 ± 4.60 IGWS-149-M3 3 16.67 ± 2.52 1.18 ± 0.20 1.93 ± 4.25 IGWS-149-M3 8 14.38 ± 1.73 0.89 ± 0.11 4.44 ± 1.18 IGWS-149-M3 12 15.62 ± 3.00 0.87 ± 0.14 -1.08 ± 3.89 IGWS-149-M3 17 28.93 ± 3.23 1.09 ± 0.18 -1.96 ± 3.01 IGWS-149-M3 19 15.74 ± 1.79 0.91 ± 0.11 0.13 ± 0.06 IGWS-149-M3 31 16.54 ± 2.06 0.92 ± 0.12 0.36 ± 0.66

Figure B-6: Radial plot for IGWS-149. Central age model used for age calculation.

114

Table B.8: Aliquots used in luminescence age calculation for IGWS-150. The following parameters were taken into consideration when choosing aliquots for age calculation: (1) Error < 25% of the measured age, (2) Recycling Ratio between 0.8 and 1.2, (3) Recuperation between -10% and +10%.

Filename Disc# Equivalent Dose (Gy) Recycling Ratio Recuperation (%) IGWS-150-M1 5 13.36 ± 1.5 1.06 ± 0.14 3.14 ± 2.52 IGWS-150-M1 9 31.03 ± 4.71 0.81 ± 0.27 -5.09 ± 6.83 IGWS-150-M1 3 83.46 ± 9.30 0.96 ± 0.34 0.87 ± 3.36 IGWS-150-M1 14 44.34 ± 7.50 0.87 ± 0.11 -0.16 ± 0.73 IGWS-150-M1 16 32.87 ± 3.44 0.92 ± 0.12 -0.16 ± 0.51 IGWS-150-M1 18 43.34 ± 9.44 0.81 ± 0.23 6.03 ± 6.08 IGWS-150-M1 22 34.17 ± 3.67 0.96 ± 0.12 0.03 ± 0.07 IGWS-150-M1 24 18.43 ± 4.58 1.06 ± 0.32 -1.40 ± 12.76 IGWS-150-M1 39 26.02 ± 3.11 0.95 ± 0.13 -0.99 ± 1.55 IGWS-150-M2 18 16.83 ± 1.55 0.91 ± 0.12 -0.23 ± 1.45 IGWS-150-M2 19 28.14 ± 2.68 0.98 ± 0.15 -2.95 ± 2.16 IGWS-150-M2 21 28.51 ± 4.40 1.07 ± 0.26 -8.69 ± 7.53 IGWS-150-M2 22 28.57 ± 4.63 1.07 ± 0.19 1.97 ± 3.19 IGWS-150-M2 30 38.54 ± 6.08 1.03 ± 0.26 9.14 ± 6.50 IGWS-150-M2 33 35.75 ± 4.13 0.99 ± 0.29 -1.36 ± 5.17 IGWS-150-M2 38 39.43 ± 5.91 0.91 ± 0.15 -0.03 ± 2.32 IGWS-150-M3 19 27.18 ± 4.41 0.80 ± 0.16 -3.59 ± 4.84 IGWS-150-M3 21 29.30 ± 3.56 1.07 ± 0.22 3.23 ± 5.20 IGWS-150-M3 33 16.41 ± 3.43 1.00 ± 0.16 9.73 ± 4.77 IGWS-150-M3 38 43.08 ± 4.95 0.88 ± 0.16 3.33 ± 2.59 IGWS-150-M3 39 28.05 ± 2.86 1.05 ± 0.15 1.27 ± 1.93 IGWS-150-M4 3 20.77 ± 4.98 1.04 ± 0.30 -0.89 ± 9.32 IGWS-150-M4 6 42.37 ± 5.25 0.99 ± 0.12 0.10 ± 0.06 IGWS-150-M4 13 22.13 ± 2.80 0.90 ± 0.15 0.13 ± 4.29 IGWS-150-M4 20 28.71 ±5.08 0.84 ± 0.14 5.14 ± 4.05 IGWS-150-M4 33 36.14 ± 6.93 0.92 ± 0.12 1.86 ± 1.28

115

Figure B-7: Radial plot for IGWS-150. Minimum age model used for age calculation.

116

Table B.9: Aliquots used in luminescence age calculation for IGWS-153. The following parameters were taken into consideration when choosing aliquots for age calculation: (1) Error < 25% of the measured age, (2) Recycling Ratio between 0.8 and 1.2, (3) Recuperation between -10% and +10%.

Filename Disc# Equvalent Dose (Gy) Recycling Ratio Recuperation (%) IGWS-153-M1 1 47.50 ± 5.65 0.99 ± 0.16 1.09 ± 2.84 IGWS-153-M1 2 9.88 ± 1.01 1.04 ± 0.13 6.31 ± 0.91 IGWS-153-M1 3 23.46 ± 2.46 1.06 ± 0.14 -1.89 ± 2.59 IGWS-153-M1 4 17.24 ± 2.40 1.00 ± 0.15 1.10 ± 5.18 IGWS-153-M1 5 25.08 ± 2.65 0.95 ± 0.13 0.52 ± 2.40 IGWS-153-M1 6 12.35 ± 2.03 1.11 ± 0.15 -1.73 ± 2.93 IGWS-153-M1 7 10.59 ± 1.71 1.00 ± 0.14 2.25 ± 3.68 IGWS-153-M1 10 10.91 ± 1.76 1.11 ± 0.14 -1.51 ± 2.01 IGWS-153-M1 15 13.42 ± 1.40 1.08 ± 0.14 2.37 ± 2.94 IGWS-153-M1 17 17.52 ± 3.24 0.93 ± 0.14 9.46 ± 7.18 IGWS-153-M1 20 9.16 ± 1.56 1.08 ± 0.15 1.55 ± 6.26 IGWS-153-M1 22 15.09 ± 1.85 0.98 ± 0.12 1.66 ± 0.77 IGWS-153-M1 23 8.96 ± 1.19 1.04 ± 0.14 2.32 ± 4.75 IGWS-153-M1 25 23.36 ± 3.02 0.95 ± 0.12 2.99 ± 0.61 IGWS-153-M1 27 15.58 ± 1.81 1.07 ± 0.13 0.19 ± 1.17 IGWS-153-M1 28 13.75 ± 1.73 0.94 ± 0.12 0.81 ± 3.14 IGWS-153-M1 29 14.93 ± 2.91 0.91 ± 0.16 -2.97 ± 10.19 IGWS-153-M1 30 14.07 ± 1.76 0.99 ± 0.12 0.39 ± 0.60 IGWS-153-M1 31 15.28 ± 2.51 0.91 ± 0.14 -2.37 ± 6.77 IGWS-153-M1 32 18.50 ± 2.34 1.01 ± 0.14 0.79 ± 3.85 IGWS-153-M1 33 10.42 ± 1.20 0.97 ± 0.12 0.38 ± 0.16 IGWS-153-M1 37 13.60 ± 2.25 1.01 ± 0.15 5.00 ± 5.74 IGWS-153-M1 40 25.53 ± 4.63 0.89 ± 0.11 1.53 ± 1.07

117

Figure B-8: Radial plot for IGWS-153. Central age model used for age calculation.

118