1

Dating the Cheops Glacier with

Lichenometry, Dendrochronology and Air

Photo Analyses

By:

Janek Wosnewski, Sean Hillis, Dan Gregory and Kodie Dewar

December 09, 2009

Geography 477 Field School

Instructor: Dr. James Gardner

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Table of Contents

1.0 Introduction ..…………………………………………………………... 3

1.1 Background Information …………………………………………3

1.10 Cirque Glacier ………..…….………..….……….……….5

1.11 Dendrochronology …..…………………………....……...6

1.12 Lichenometry ……….……….…………………………...7

2.0 Site Description …..……………………………………………….….…9

2.1 Description ……………...………………………………….….…9

2.2 Climate …………………………………………………….…..…9

3.0 Dendrochronology …………………………………………………..…12

3.1 Methods ……………………………………………………....…12

3.2 Results ……………………………………………………......…14

3.3 Sources of Error…………………………………………....……15

4.0 Lichenometry …………………………………………………….....…16

4.1 Methods ……………………………………………………...…16

4.2 Results ……………………………………………………..……17

4.3 Sources of Error……………………………………………....…19

5.0 Discrepancies in Lichenometry and Dendrochronogoly Data ……...…21

6.0 Air Photo Analysis…………………………………………………..…22

6.1 Results …………………………………………………..………27

6.2 Sources of Error ………………………………………...………28

7.0 Discussion and Conclusion…………………………………….....……29

8.0 References………………………………………………….………......31

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1.0 Introduction

1.1 Background Information

Glacier National Park which was established in 1886 is situated in the

Columbia Mountain regions of British Columbia and hosts a wide variety of

plants, animals and ecosystems (Parks Canada, 2009). The park protects a

wide variety of plant and animal life and has a specific management plan for

each of the others that are of concern. The history in the park, particularly in

the Rogers Pass area is very unique. Rogers pass is home to a national

historic site known as Glacier House which was a luxurious hotel that hosted

the many travelers brought in on the Canadian Pacific Railway and was a

pioneer in the mountain hotel business. The Columbia Mountains are

extremely rugged with steep terrain and are subjected to harsh climate

conditions. The geomorphology is unlimited with the combination of steep

terrain and large annual precipitation. There are numerous alpine glaciers

and fluvial systems throughout the park that are constantly eroding the ever

changing landscape.

Glacier National Park is ~135 000 hectares and has an elevation at

Rogers pass of 1382m with many mountains in the region reaching heights

of 2500 metres. The park is situated in the Columbia Mountain range east of

Revelstoke BC, specifically in the Selkirk and Purcell ranges. In the Rogers

Pass area there are permanent buildings such as a Ski lodge and a Parks

Canada Maintenance yard. In the summer months the area is full of avid

hikers and when the winter hits adventurous ski touring groups take over.

The TransCanada Highway runs through the park and the largest avalanche

control program in the world is operated by Parks Canada in this very pass.

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The parks goals are to protect the plants and animals in the region and

preserve the natural beauty of the area. The dominant tree species in the

region consist of old growth Cedar and Mountain Hemlock stands. The

major big game animals that are being monitored are grizzly bears, mountain

caribous and mountain goats. Throughout the park there are numerous trails

that lead into the alpine, many of which have been there since the park was

establish and were built by Swiss guides that were brought to the area.

Glacier National Park was the first park in BC and has a very unique

history to it. Within the park is Rogers Pass which is named after Major

A.B. Rogers, who found the route after a long and treacherous journey for

the Canadian Pacific Railway in 1885 (Parks Canada, 2009). The new

railroad brought many adventurous travels west to seek to lives and to

experience the Rocky Mountains. The Rogers Pass area was starting to

become a very luxurious place to visit because of the wonderful scenic

views in the summer and also the wonderful ski touring in the winter.

Glacier House was the first hotel in the region and quickly grew to

accommodate the massive influx of travels. Glacier House, now dismantled,

is part of a national historic site in the Rogers Pass area and is viewed as the

inspiration of similar buildings and services such as Banff Springs, Hotel

Vancouver and Chateau Lake Louise (Parks Canada, 2009).

The steep terrain and high precipitation give rise to some of the most

interesting geomorphology in the world. Glaciers once covered the majority

of Canada and now they cover less than 10% (Parks Canada, 2009). In

Glacier National Park there are many alpine glaciers including the

Illecillewaet formally known as the Great Glacier, the Asulkan, and the

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focus of this project, the Cheops glacier. The formations left behind by

these glaciers show a history and if studied properly can tell a story of how

these formations were formed.

Figure 1 - Glacier National Park of Canada (Parks Canada, 2009).

1.10 Cirque Glacier

Glaciers are defined as a body of moving ice that has been formed on

land by compaction and recrystallization of snow (Ritter et al, 2002). There

are two major requirements that must be met before an ice mass can be

considered a glacier; these being the formation of the ice mass must be from

the accumulation and metamorphism of snow as well as the ice must be

moving internally or as a sliding block (Ritter et al, 2002). Throughout the

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literature glaciers have been classified based on a number of morphological,

dynamic and thermal properties including size and growth environment

(Ritter et al, 2002); however Flint (1971) suggests that glaciers can be put

into three broad categories that include cirque glaciers, valley glaciers and

ice sheets. Cirque glaciers, like the one that is present in our study area, are

defined as: Flowing ice streams restricted to amphitheatre-shaped

depressions in valley headlands (Ritter et al, 2002).

1.11 Dendrochronology

Dendrochronology is defined as the science that deals with the dating

and study of annual growth layers in trees or shrubs, commonly referred to

as tree rings (Smith and Lewis, 2007a). Tree rings form as a result of

cambium cells being active during the spring when the xylem cells produced

are large and thin-walled, and dormant during the winter when xylem cells

are smaller and thick-walled (Smith and Lewis, 2007a). Xylem cells that

form in the active growing season are commonly known as spring or

earlywood, where cells that form in the dormant months are known as

summer or latewood; it is this distinct difference between early and latewood

cells that allows for the identification of annual growth rings (Smith and

Lewis, 2007a).

Dendrochronology as a scientific discipline has many different

applications and branches which date as far back as the 15th century when

Leonardo da Vinci observed the annual nature of tree-rings through the

relationship between their widths and precipitation (Smith and Lewis,

2007a). Of the several branches that make up dendrochronology including

dendroglaciology, dendroclimatology and dendrogeomorphology;

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dendroglaciology is the branch that most caters to this report due to its use of

tree rings to date the movement of glaciers as well as the age of moraines

and other glacial deposits (Smith and Lewis, 2007b).

The dating of glacial moraines is a multi step process that involves

counting the number of rings at the base of the moraines oldest tree to

determine its minimum age (Koch, 2009). Next a value that take into

account the lag period between glacial retreat or moraine formation and tree

germination is added to the age of the oldest tree to give the true age of the

moraine (Smith and Lewis, 2007b; Mcarthy and Luckman, 1993). This lag

period, known as the ecesis rate, is a site specific value because germination

times can be greatly affected by differing geology, topography and

microclimate (Koch, 2009). The ecesis rate for an area can be obtained

through a number of techniques including taking tree-ring or seedling

samples from an area of know age or using air photos of the area to estimate

the rate of glacial retreat (Mcarthy and Luckman, 1993).

1.12 Lichenometry

Spatial analysis of moraines can be difficult to achieve because they

are often subject to significant modification during subsequent phases of

glacial advance and retreat. Interpretation of past glacial activity becomes

complicated due to variable ice margin activity over time. For example:

individual moraines can be unique and reveal evidence of bifurcation and

cross cutting patterns from differential ice retreat (Bennet, 2001).

Prominent glacial depositional features such as terminus, lateral, and

medial moraines are deposited during phases of glacial retreat. These

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features are often deposited in a uniform manner which suggests a steady

rate of glacial recession. This means that the depositional material forming

the moraine will be of similar age and subject to similar post-depositional

environmental, geomorphic, and glacial modification, thus suggesting that

these surfaces will have similar history. The identification of these surfaces

may provide a useful method to identify the location or extent of former ice

margins (Dugmore et al, 2008).

Once these surfaces are exposed, they are susceptible to invasion from

plant colonization (McCarthy & Luckman, 1993). The fastest known

colonizing species on a substrate surface is lichen. The colonization and

growth of lichen allows for study and analysis of the surface on which it is

found. More specifically, the analysis of its growth is referred to as

lichenometry and is a technique that has been used extensively for the dating

of geomorphic features in the past (Lindsay, 1973).

Lichenometry is a calibrated-age dating technique used to establish a

minimum surface date of rocks using measurements of lichen thallus

diameter (Allen & Smith, 2007). The lichen diameter is measured and

correlated to the age of the surface it is found on, whether it is wood, dirt, or

substrate. It is a technique that was first introduced in the early 1930's but

was later developed by Roland Bechel who brought it to the forefront of the

scientific community (Lindsay, 1973; Webber & Andrews, 1977).

Lichenometry uses the assumption that a lichen thallus diameter is

proportional to the lifespan or time that a lichen has grown on a surface, and

in turn is proportional to the age of the surface on which it is found.

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In this study we use the lichenometry dating technique to determine the

age of the depositional moraines found within the Mount Cheops glacier

region. This technique, in combination with dendrochronology and air

photo analysis, is ultimately used to determine the different historical ice

margins of the Mount Cheops glacier.

2.0 Site Description

2.1 Cheops site

The Cheops glacier is located in the cirque on Cheops Mountain and

is reached from the Balu Pass trail. To reach the glacier you must travel up

the trail ~2km then venture South off the path and up a creek bed to the site.

Cheops Mountain is at ~2650m elevation and has moderate to extremely

steep terrain. The cirque faces north which means it is sheltered from the

sun and it is this very attribute that has prolonged the life of the Cheops

glacier. An interesting situation occurred when Parks Canada was

questioned about the Cheops glacier and they responded by saying that there

was no glacier in the Cheops cirque. This goes to show how much of a

hidden gem the Cheops glacier really is.

2.2 Climate

Climate plays one of the largest roles when it comes to the

advancement and retreat of a glacier. The Glacier National Park region is

subjected to winters with high snowfall and moderate temperatures (Parks

Canada, 2009). Lots of the weather forecasts in the area tend to be

unreliable because of the variations in topography which create large

barriers between adjacent valleys (Parks Canada, 2009).

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The Little Ice Age was a period of cooling and an era of advancement

for glaciers. Depending on the location it occurred anywhere from ~900 to

~650 years ago and is believed to have been the time when the alpine

glaciers in the Revelstoke area reached their farthest extent. As quoted by

Koch et al (2007), “The glaciers reached their furthest extents between

1690-1720.” This extent is marked by the terminal moraine and on the

Cheops glacier sufficient evidence was gathered in order to produce an age

of when the glacier reached its maximum.

Climate change in the Glacier National Park area consists of warming

temperatures and decreasing precipitation amounts. In figures 2.21 and 2.22

it can be seen that these events are happening at an alarming rate. Since the

1960’s the mean annual temperature has increased approximately by 1.5oC

and the mean annual snow fall has decreased by approximately 25cm. With

the combination of; increasing temperatures creating increased melt, and

decreasing snow fall creating less accumulation, it can be hypothesized that

the future does not look good for glaciers in the Glacier National Park area.

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Figure 2.1- Mean Temperature in Rogers Pass, B.C. since 1965.

Figure 2.2 - Mean Snowfall in Rogers Pass, B.C. since 1965.

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3.0 Dendrochronology

3.1 Methods

For the purpose of estimating the approximate age of the larger, more

heavily vegetated right lateral and medial moraines, tree core samples were

extracted with a 5mm increment borer from a number of trees found

growing on the surface of these moraines. In accordance to the principal of

replication two cores were sampled from multiple trees as close to the base

of the tree as possible (Smith and Lewis, 2007a). This principal states that

by taking multiple samples from the base of several trees in the same area,

intra-tree variability as well as the influence of undesired environmental

factors, and missing or false rings will be reduced when dating the glacial

feature (Smith and Lewis, 2007a). In total 10 cores were collected from the

east lateral moraine and 14 cores were collected from the medial moraine.

When trees were deemed too small to be cored their whorls were counted

assuming that each whorl represented a year of growth. This procedure was

applied to trees growing on two glacial scars in order to date the time of their

formation. In addition branch samples were taken of the trees for the purpose

of species identification. All trees growing on the east lateral and medial

moraines were identified to be Sub-Alpine Fir.

Approximately fifteen tree core samples were extracted from a

number of large trees (identified to be Hemlock) growing west of the medial

moraine. This was done for the purpose of estimating the maximum extent

of the glacier in our study area. According to Koch et al. (2007) glaciers in

the Coast Mountains reached their maximum extent in the Little Ice Age

between the dates of A.D. 1690 and 1720. Unfortunately the majority of the

oldest trees in this area were rotten and only 4 of the extracted cores were

able to be analyzed and dated. The annual growth layers of these 4 tree core

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samples were counted and after an ecesis rate (calculated for Hemlock trees

on the Illecillewaet glacier) was applied, the formation the substrate in this

area was dated back to 1643 (See Table 3.1). This date precedes the period

of glacial maximum extent suggested by Koch et al. (2007) and establishes

that the glacier never reached this point of our study area.

After the required samples had been taken tree core and branch

samples were transported to the University of Victoria Tree Ring Lab for

analysis. Tree core samples were glued onto wooden blocks and sanded

multiple times in order to make the individual rings more distinguishable

and easier to count. The use of a microscope aided in the counting of

individual rings which were recorded using the program WinDendro. Ring

counts were than analyzed to determine the oldest tree on each of the

moraines for the purpose of applying an ecesis rate to determine the actual

age of the moraines.

The determination of an ecesis rate unique to our study area proved to

be a difficult task due to a lack of areas of known age within our region, or

aerial photographs showing maximum glacial extent. If these pieces of

information had been available they could have been utilized to calculate an

ecesis rate specific to our study site. This lack of prior data forced the use of

previously determined ecesis rates calculated for the Asulkan and

Illecillewaet glaciers by McCarthy and Luckman in 1993 and 2003. These

ecesis rates are not ideal but were considered to be valid for determining the

age of the moraines in our study area because they have been calculated for

Sub-Alpine Fir and Hemlock trees (the same species of tree we collected

cores from) and because the Illecillewaet and Asulkan glaciers are located in

a microclimate similar to our study area. These ecesis rates, determined to

be 45 years for the Asulkan glacier and 35 years for the Illecillewaet glacier

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(Mcarthy and Luckman, 1993 and Mcarthy 2003), were added to the age of

the oldest tree found on the right lateral and medial moraines to give an

estimate of their age (see Table 3.2 and Table 3.3). An ecesis rate of 40

years was applied to the Hemlock trees growing west of the medial moraine

in accordance to the Illecillewaet ecesis rate calculated for Hemlock trees.

3.2 Results

Table 3.1- Date and age of area west of medial moraine

Tree Species: Hemlock

Ecesis Rate: (40 yrs Illecillewaet)

Germination

Date of Oldest

Tree

Age (yrs) of

Oldest Tree

Age of Substrate

With

Illecillewaet

Ecesis Rate

Date of Area

1683 326 366 1643

Table 3.2-Date and Age of East Lateral Moraine

Tree Species: Sub-Alpine Fir

Ecesis Rate: (35 yrs Illecillewaet) (45 yrs Asulkan)

Germination

Date of

Oldest Tree

Age (yrs)

of Oldest

Tree

Age With

Illecillewaet

Ecesis

Age With

Asulkan

Ecesis

Date of

Moraine

With

Illecillewaet

Ecesis

Date of

Moraine

With

Asulkan

Ecesis

1926 83 118 128 1891 1881

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Table 3.3-Date and Age of Medial Moraine

Tree Species: Sub-Alpine Fir

Ecesis Rates: (35 yrs Illecillewaet) (45 yrs Asulkan)

Germination

Date of

Oldest Tree

Age (yrs)

of Oldest

Tree

Age With

Illecillewaet

Ecesis

Age With

Asulkan

Ecesis

Date of

Moraine

With

Illecillewaet

Ecesis

Date of

Moraine

With

Asulkan

Ecesis

1934 75 110 120 1899 1889

3.3 Sources of Error

Possible sources of error in this project include the use of ecesis rates

not specific to our study site, false or missing tree rings, missing the pith

when tree core samples were extracted and failure to locate the oldest tree on

the feature being dated. The utilization of ecesis rates calculated for the

Asulkan and Illecillewaet glaciers may have resulted in the dates of the

moraines in our study area being over or under estimated. While these

glaciers are in close proximity to our study area slight differences in

microclimate, topography, geology and elevation could cause the

germination rates in these areas to be different from our study area (Koch,

2009). The presence of false rings in our tree core samples could have

caused over estimation of moraine age while under estimation could have

been the result of missing rings or failure to locate the oldest tree on the

moraine (Koch, 2009). Failure to reach the pith of the tree in our tree core

samples was not a direct source of error for our project as all our sampled

cores included the pith, however if the pith had been missed reliance on the

estimation of missing rings could have caused ages to be over or under

estimated (Koch, 2009).

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4.0 Lichenometry

4.1 Methods

Lichen sampling for the Mount Cheops glacier study site was

conducted on the most prominent glacial features in the area. These features

consisted of 3 major moraines; two lateral moraines on the eastern side of

the site and one medial moraine on the western portion. There was a large

moraine that was formed into the mountain side on the most western side of

the Mount Cheops glacial site but was not sampled due to its extremely steep

topography and dangerous climbing conditions. Lichens were sampled from

the entire top ridge of each moraine, while careful measures were taken to

avoid sampling on the proximal and distal sides.

For each moraine a total of 30 lichen samples were collected. Each

moraine was broken into 6 sample areas, from which 5 samples were taken

at each site. The sample sites were evenly distributed over the entire span of

the moraine to allow an adequate representation of lichen cover for each. 10

lichen samples were also collected from the remnants of a small moraine

located directly below the western medial moraine on the eastern side.

Because only 10 samples were collected, the validity of dating this feature

may not be adequate. This moraine looked like it lined up with the lower

eastern lateral moraine so dating this feature was attempted; however it was

not the main focus of study.

The lichen species of focus were healthy yellow/green Rhisocarpon

geograhicum, which are renowned for their long life spans and slow growth

rates (Benedict, 1988). Only the maximum diameter of the largest lichen

thallus was sampled because it is assumed that maximum thallus diameter

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possess the optimum growth rate and is indicative of the oldest substrate age

(Calkin and Ellis, 1980). Also, only the circular or ellipsoidal lichens were

considered for measurement. These sample restrictions were applied while

sampling thalli on each moraine and therefore allowed for consistency

suitable for comparison between each feature.

The lichen thalli measurements were taken with a digital caliper and

were measured with an accuracy of +/- 1 mm. Each thallus sample involved

two measurements; one at the horizontal x-axis of the thallus, and one

directly perpendicular to the first, at the y-axis. These values were recorded

and stored for further analysis.

Calculations of the samples included the determining the mean of the

x-axis and y-axis thalli measurements for each sample. This was done to

decrease the chances of over or underestimating the substrate age based on

the measurements. The mean of each moraine was then calculated to give an

overall representative lichen thallus size for each feature. The mean lichen

thallus for each moraine was then applied to the McCarthy Growth curve of

the Illicilewaet glacier (McCarthy, 2003).

4.2 Results

The mean Rhizocarpon geographicum lichen diameter was calculated

for each land form and applied to the McCarthy Growth Curve as shown in

figure 4.1. The lichen thalli diameters applied to the growth curve are the

best representation of each individual moraine's overall thallus size. The

respective thalli diameters are as follows. The lower eastern lateral moraine

mean thallus diameter was 33.34 mm, which produces a substrate age of 110

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years. Next was the upper eastern lateral moraine, giving a mean thallus

diameter of 53.70 mm which produces a substrate age of 170 years. The

western medial moraine had a mean thallus diameter of 59.56 mm, which

generates a substrate age of 201 years.

Lower Eastern Lateral Morainex = 33.34mm y = 110 years old

Upper Eastern Lateral Morainex = 53.70mm

y = 170 years old

Western Medial Morainex = 59.56mm y = 201 years old

Figure 4.1 - Lichen Growth Curve for the Illecillewaet Glacier (McCarthy, 2003)

The remnants of the small moraine located directly below the western

medial moraine on the eastern side provided a mere 10 lichen samples. This

was due to the proportion of the feature's size compared to the other

moraines studied. With only ten samples, the credibility of lichenometric

dating on this feature may be invalid. However, the mean thallus diameter

was 39.28 mm and when applied to the McCarthy growth curve, provides a

substrate age of 123 years. The respective ages of the moraines are shown in

table 4.2.

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Table 4.2 - Mean thallus size, age, and depositional year for each moraine

Thallus

Diameter Age Respective Year

Lower Eastern

Lateral Moraine 33.34 mm 110 years 1899

Upper Eastern

Lateral Moraine 53.70 mm 170 years 1839

Western Lateral

Moraine 59.56 mm 201 years 1808

Lower Western

Moraine

Remnants

39.28 mm 123 years 1886

4.3 Sources of Error

It is important to look at factors that may influence lichen growth

because favorable conditions may skew substrate dating results.

Lichenometry in the past has been criticized for its absence of recognition of

ecological factors that influence the growth rates of lichens. However, it is

now assumed that both streams and snow cover have an effect on the growth

rates of Rhizocarpon lichens (Innes, 1985). Studies from the past indicate

that moisture availability and proximity to streams or lakes promote growth

in rhizocarpon thalli. Snow cover on the other hand tends to restrict lichen

growth and limit the surface availability that lichen grow on. Also, close

proximity to snow cover often results in smaller lichen thalli than usually

expected (Innes 1985).

These factors may influence our findings because both of the eastern

lateral moraines were close to glacial ice and water. There was no snow

cover on any of the substrate however; the eastern tongue of the Mount

Cheops glacier ran parallel to the upper portion of the eastern lateral

20

moraine. According to Innes (1985), the proximity of this ice may have

inhibited the growth rate and influenced the size of our sampled thalli. The

lower portion of the secondary eastern lateral moraine is also susceptible to

this information because the glacial melt water formed the headwall of a

stream which ran parallel to this feature. According to Innes (1985), this

proximity to moisture may have increased the growth rate of the sampled

lichen on the lower portion of the lower eastern moraine and may have

influenced our results.

Luckman (1977) outlines two important variables that also may

contribute to dating errors when using lichenometry. Firstly he raises the

issue similar to that Innes (1985) in regards to lichen growth rate variability

on both a regional and local scale. The lichen growth rate variability can be

influenced by factors such as moisture availability, temperature, duration of

snow cover, and the composition of the host substrate itself. Secondly, he

mentions that the use of the largest lichen thalli as indicators of substrate age

may contribute to error. Larger lichen may be found on older substrate

debris and favorable local environmental conditions may also result in

abnormally large lichen growth rates.

A significant factor that may increase error in our lichenometry dating

is the fact that we did not use a lichen growth curve constructed specifically

for our glacier. We instead used McCarthy’s Illecillewaet lichen growth

curve which was designed specifically for the Illecillewaet glacier. This

growth curve was chosen because the Illecillewaet glacier is located in the

same general region, has a comparable elevation, and similar micro climate

to the Mount Cheops glacier. Although these factors may produce a similar

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lichen growth rates between the two sites, Mount Cheops may be different

and using a non specific growth curve may skew results.

It is also important to note that an ecesis value was not used in our

lichenometry technique. An ecesis rate refers to the time interval between

the exposure of a substrate and the colonization of a species such as lichen

(McCarthy, 2003). Although it is an important aspect of lichenometry, it was

not incorporated in the lichenometric dating of Mount Cheops moraines.

This because the McCarthy growth curve was used to determine our

substrate dates. The McCarthy growth curve directly relates the lichen thalli

diameters to the age of the surface they are found on. It is in this relationship

that we assume the ecesis value is incorporated. Thus an ecesis value was

not added to the age produced when correlating our lichen thalli diameters to

the growth curve.

5.0 Discrepancies in Lichenometry and Dendrochronogoly Data

The discrepancies in dates between lichenometry and

dendrochronogoly data can be explained by the frequent high magnitude

avalanches that are seen throughout this area (Parks Canada, 2009). The

impacts of avalanches on the slopes of the site would limit the seeding

establishment in the pathways of avalanches (S.J. Walsh, 1994). On the

other hand, lichen establishment is quick and can occur over the course of

one summer. Therefore, discrepancies in dates are within reason and are

reasonable when including sources of error.

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Figure 6.1 – Estimated recessional lines -1951 A, D, L

represent Air photo analysis dates, Dendrochronogoly data

dates, and Lichenometry data dates respectively.

6.0 Air Photo Analysis

Air photo analysis

proved to be a very

useful tool is

assessing the

Cheops glacier.

With only a ground

level view of the

glacier, the aspect

of the air photos

allow for a clear

image of the site.

Air photos were

gathered from the

Air Photo

Warehouse at the

Interurban

Camosun College

campus in Sannich,

B.C. dating back to

1951, 1986 and 1991. Prior to gathering air photos of the site, location of the

terminus was under scrutiny among group members due to the orientation of

the site, fluvial deformations, debris cover, and vegetation cover. Air photos

from 1951 clearly revealed the location of the glacial terminus through the

lack of vegetation cover and deformation (Fig. 6.1).

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Figure 6.2 – Air photos taken in 1986

Air photos

taken in 1986

provided the

clearest image of

the site (Fig. 6.2). It

was speculated that

two separate

accumulation zones

located at nearest to

the head wall lead

to the formation a

the distinct western

medial moraine.

Furthermore, since

1951, there has

been extensive

deformation to the

terminal area due to

glacial outwash. It

can be also noted that large scale deformations occurred to the area above

the red line in Figure 6.1. The development of thermokarst type topography

could be seen through the debris that remained on the glacier in this same

area in air photos from 1986.

In comparison to the air photo taken in 1951, the relationship of the

terminal moraine to the eastern most lateral and western medial moraines

24

Figure 6.3 – Estimated recessional lines - 1986. A, D, L represent Air photo

analysis dates, Dendrochronogoly data dates, and Lichenometry data dates

respectively.

found at higher elevations was established. Thus, was dated through

dendrochronogoly to 1881-1891 and 1808 through lichenometry (Fig. 6.3).

Scars found on the proximal side of the lower west medial moraine and their

corresponding recessional moraines seen in Figure 6.2 laid the path of the

date lines drawn in Figure 6.3.

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Figure 6.4 – Orange line represents the farthest most extent of the Cheops Glacier on

either side of the medial moraine. Star and Diamond represents tree ring dates of

Mountain Hemlocks with an implied 40 year ecesis value

Due to the lack of time and man power, data collected to the areas

west of the medial moraine was limited. However, tree ring data retrieved

from a Mountain Hemlock species in this area lead to the estimated path and

extent of the glacier west of the medial moraine (Fig 6.4). This group of

26

trees was situated away from the main avalanche corridor such that seedling

establishment would not be impacted. Underlying substrates of Mountain

Hemlock trees cored and dated to 326 years and 168 years, with an implied

an ecesis value of 40 years, dated to 1643 A.D and 1801 A.D. respectively.

The trees dated to 1801 A.D. matched up nicely with the lichenometry dates

of the terminal moraine. However, trees dates back to 1643 A.D. provided

some confusion as why how this tree may be related to the Cheops Glacier.

In fact, during the Little Ice Age, glaciers achieved their greatest extent

between A.D. 1690 and 1720 (Koch, 2007) which would lead one to believe

that the Cheops Glacier itself achieved its greatest extent around these same

dates. This lead to the conclusion that the Cheops Glacier, during the Little

Ice Age, did not reach the extent of the tree dated to 1643A.D. and thus the

corresponding date lines in Figure 6.4 were established.

Air Photos proved to be very useful for the locating lateral, medial,

terminal, and recessional moraines that were otherwise tough to pick out on

the ground. When relating data from what was found through

dendrochronogoly and lichenometry with the air photo analysis, the

understanding of the geomorphology processes that took place at this site,

along with their corresponding dates in which then occurred, are evident.

27

Figure 6.5 – Estimated recessional lines - 1991 A, D, L represent Air photo

analysis dates, Dendrochronogoly data dates, and Lichenometry data dates

respectively.

6.1 Results

Through basic air photo interpretation, retreat rates were established to the

air photo taken in 1991 (Fig 6.5). Its scale was calculated through

relationships to topographic maps and was determined to be 1:14000. From

28

this retreat rates were calculated and classified into different time periods

(Table 6.1).

Table 6.1 – Retreat rates according to time periods

Time Period (A.D.) Retreat Rates (m/year)

1808-1949

1949-1956

1956-1986

1986-1991

1.45

2.01

3.73

5.60

6.2 Sources of Error

The methods used in calculating the scale of air photos entailed the

use of topographical maps that had scales much smaller than those of the air

photos used. Consequently, the smaller scales of the topographical maps

may have been rounded and not accurate.

Air photo interpretation and the above results were calculated used

standard rulers for measurements. Subsequently, human error would be large

contribution in the error in the results section of the air photo analysis.

Throughout the calculation process, measurement on air photos had an

accuracy of 1mm and a higher level of accuracy may have bettered the

results.

The location of green and yellow recessional lines located in Fig. 6

above were estimated and may not have been the precise locations of ice at

their given dates. Had the air photos been taken in color or false-color, it

may have been easier to locate the extent of the ice at the time the air photos

were taken because boundaries of ice and debris would be more distinct.

29

Moreover, there debris on the surface of the glacier may have covered ice

and masked the true glacial extents at the time the photos were taken.

7.0 Discussion and Conclusion

Lichenometry and Dendrochronology were quantitative procedures

used in order to find specific dates of moraines left by the Cheops cirque

glacier. Air photo analysis was a qualitative process that was also used to

date the moraines. Through the use of the first two methods in the field and

the third method in the labs, the dates of the moraines were found and a

history of the glacier was created.

It is very evident all around the Glacier national park area that glaciers

are retreating at a substantial rate. This is a direct result of changing climate

which was pointed out in figures 2.21 and 2.22. It is very easy to see the

retreat if you have access to Air Photos of the area. The Air Photos

collected for this study proved to be extremely useful. They showed

significant retreat and from these photos retreat rates were estimated. The

estimated retreat rates increased as time went on and are currently greater

than 5.6m/yr.

It was determined that the Cheops cirque glacier was actually two

glaciers which was concluded by the medial moraine seen in the field and in

the air photos. The extent of these glaciers was extremely different because

of the topography in the area. The Eastern most glacier reached an extent

that can be seen by a terminal moraine (Figure 6.5). The Western most

terminated over a very steep cliff face and therefore did not have a terminal

moraine.

30

The results that were found through the use of the three processes

correlated very nicely to other studies. It was found that the Cheops glacier

reached its extent in an era known as the Little Ice Age. The late advances in

the Little Ice Age occurred around the late 1600’s to early 1700’s which

correlates to the dates of the moraines that were interpreted through the three

study methods (Koch et al, 2007).

31

8.0 References:

Allen, S.M. and Smith, D.J. (2007). Late Holocene glacial activity of Bridge

Glacier, British Columbia Coast Mountains, Canadian Journal of

Earth Science, 44: 1753-1773.

Benedict, J. B. (1988). Techniques in Lichenometry: Identifying the Yellow

Rhizocarpons, Arctic and Alpine Research, 20 (3): 285-291.

Calkin, P.E. and Ellis, J.M. (1980). A Lichenometric Dating Curve and its

Application to Holocene Glacier Studies in the Central Brooks Range,

Alaska, Arctic and Alpine Research, 12(3): 245-266.

Dugmore, A. J., McKinzey, K. M., Orwin, J. F., Stephens, M. A.( 2008).

Identifying Moraine Surfaces with Similar Histories Using Lichen Size

Distributions and The U2 Statistic, Southeast Iceland, Geografiska

Annaler Series A: Physical Geography, 90 (2): 151-164.

Innes, J. L. (1985). Moisture Availability and Lichen Growth: The Effects of

Snow Cover and Streams on Lichenometric Measurements, Arctic and

Alpine Research, 17(4): 417-424.

Lindsay, D.C. (1973). Estimates of Lichen Growth Rates in the Maritime

Antarctic, Arctic and Alpine Research, 5(4): 341-346

Koch, J. Clague, J.J., Osborn, G.D. (2007). Glacier fluctuations during the

past millennium in Garibaldi Provincial Park, southern Coast

Mountains, British Columbia, Canadian Journal of Earth Science, 44:

1215-1233.

Koch, J. (2009). Improving Age Estimates for Late Holocene Glacial

Landforms Using Dendrochronology-Some Examples from Garibaldi

Provincial Park, British Columbia, Quaternary Geochronology, 4:

130-139.

Luckman, B. H. (1977). Lichenometric dating of Holocene moraines at

Mount Edith Cavell, Jasper, Alberta, Canadian Journal of Earth

Science, 14: 1809-1822.

32

McCarthy, D.P and Luckman, B.H. (1993). Estimating Ecesis for Tree-Ring

Dating of Moraines: A Comparative Study from the Canadian

Cordillera, Arctic and Alpine Research, 25: 63-68.

McCarthy, D.P. (2003). Estimating Lichenometric Ages by Direct and

Indirect Measurement of Radial Growth: A Case Study of Rizocarpon

agg. At the Illecillewaet Glacier, British Columbia, Arctic, Antarctic,

and Alpine Research, 35(2): 203-213.

Park Canada. 2009. Glacier National Park – Avalanche Awareness.

Accessed December 2, 2009 from http://www.pc.gc.ca/eng/pn-

np/bc/glacier/activ/activ9.aspx.

Ritter, D. F., Kochel, R. C., & Miller, J. R. (2002). Process Geomorphology

(4th ed., pp. 297-299). Long Grove, IL: Waveland Press Inc.

Smith, D. and Lewis, D. (2007a). Dendrochronology, Encyclopedia of

Quaternary Science. Edited by: S.A. Elias. Elsevier Scientific, 1: 459-

465.

Smith, D. and Lewis, D. (2007b). Dendroglaciology, Encyclopedia of

Quaternary Science. Edited by: S.A. Elias. Elsevier Scientific, 2: 986-

994.

Walsh, S.J. (1994). Influence of snow patterns and snow avalanches on the

alpine tree ecotone, Journal of Vegetation Science, 5: 657-67

Webber, P. J. and Andrews, J. T., 1973: Lichenometry: A commentary.

Arctic and Alpine Research, 5 (4): 295-302.