An Examination of Glacial Processes, (Transportation, Erosion and Deposition), and the Landforms Created in Glendalough

By Henry Kulikov

Part 1:

Aims:
The aim of my research project is to investigate glacial processes and resulting features found in Glendalough.

Objectives:

  1. To investigate glacial processes and landforms in general.
  2. To draw a sketch map at the site,
  3. To draw a cross section of the valley floor and get more information about the shape of the valley,
  4. To use an Ordnance Survey map to identify the glacial features in Glendalough National Park and work out the direction that the glacial moved,
  5. To find out what is glacial erratic and how they are formed,
  6. To find an example of an erratic in Glendalough,
  7. To study the geology of the National Park and
  8. To find out about U shaped valleys and how they are formed by glaciers.
Aerial photograph of Glendalough

Aerial photograph of Glendalough

 

Map of east coast of Ireland showing Glenadalough

Map of east coast of Ireland showing Glenadalough

 

Glendalough National Park

Glendalough National Park

Part 2Planning

The journey to Glendalough required lots of preparation and organisation.
The organisation required:

  1. Equipment had to be gathered and listed,
  2. We had to rent a bus and reserve the Educational Centre in Glendalough,
  3. We had to investigate the last ice- age in Ireland,
  4. We had to research glacial processes and features using the internet/books from the library,
  5. Worksheets had to be produced.

Directions from the school we used to get to the study site using Google maps. This goes on the blank page. I will have to put on more photos on the blank page.

Part 3Introduction to gathering of data

Introduction:
This section of the full study had two parts:

The first thing I had to do was background research and the second I had to collect information at the study site.

Background research:
Before going to Glendalough National Park we collected lots of information about the park and related glacial information. We used the Internet and books from the library to find out about the last ice-age and its impact on Ireland (especially in county Wicklow) as well as glacial processes and landforms. We also investigated the history of the park, its geology and information on glacial processes and features.

Field methods

Here are the methods I used to collect data in the National Park:

Method (a): Sketch map
We drew a sketch map of the Glendalough Valley near the upper lake looking back towards the mountain. We did not make it perfect because we knew that we would have corrected it in class. Then we marked in all glacial features we could see and we also identified the rocks in the valley using the vegetation line as a guide.(put a photo of the sketch map across the page on the blank)

Method (b): Geology of the National park in Glendalough
Using the Internet we found out the main types of rock that are present in the park. The two main types of rock are:

  1. Granite
  2. Mica-schist

We then learned how to identify the rock types in the study site. It was not very hard because of their appearance they are easy to spot and we took a basic geology book with us to help this process in the field.

Method (c):  Ordnance Survey map
In Geography class we learned how to spot glacial features on a O.S map. When we went to the National Park we brought one of the maps and marked in the glacial features we found. We then marked in the direction the glacial moved to transport materials from the highland down to the lowlands.

Method (d): Measurement of the Glacial Erratic
Before measuring the glacial erratic we had to find a good example of it and the Educational Centre in Glendalough National Park show us one which we then marked in on the Ordnance Survey map. Our class’ objective was to find out how big the glacial erratic was and also to find out how strong the glaciation was in the park. We then measured the erratics height, width and its depth. With these results we could then find out its mass using a formula. We then identified the type of rock it was.

Method (e): Completing a Cross Section
We had to draw a cross section of the valley floor to find out if the valley was U – shaped or V – shaped, also we tried to get an idea of the channel that the glacial material moved through. Glaciers always have a U – shaped valley but it was our job to prove it. We started drawing it in the Glendalough National Park car park which was facing the slope. We placed a Staging Pole down and looked for the first break of the slope and put another pole when we found it. When we had the poles set up we used the measuring tape to measure the distance and using a Clinometer we found out the angle. We then did three cross sections.

Part 4: Results

Background research:

History of Glendalough National Park

Glendalough has a varied heritage in terms of history, geology, archaeology, glaciology, flora, and fauna. The Glendalough Valley was carved out by glaciers during the Ice Age and the two lakes, from which Glendalough gets its name, were formed when the ice eventually thawed. The National Park covers an area of 20,000 hectares and covers much of upland Wicklow. It has a variety of fauna and flora because of this over one million visitors come every year. Wicklow Mountains National Park was established by the government in 1991 and is managed by the National Parks and Wildlife Service.

 

Geology of Wicklow Mountains

 

420 million years ago, when the continental plates of North America and Europe collided, the land beneath the sea buckled upward. The land rose out of sea, forming the Wicklow Mountains. The Wicklow Mountains are famous forgranite rock which has been quarried for centuries. The second rock there is mica-schist

 

Glacial Processes

Glaciers, while geographically restricted, are effective agents of landscape change. The gradual movement of ice down a valley causes abrasion and plucking of the underlying rock. The debris transported by the glacier, when the glacier recedes, is termed a moraine. Glacial erosion is responsible for U-shaped valleys. Like great rivers of ice, glaciers have sculpted mountains and carved out valleys. They continue to flow and shape the landscape in many places today. Ice erosion can take one of two forms. It can be caused by the movement of ice, typically as glaciers, in a process called glacial erosion. It can also be due to freeze-thaw processes in which water inside pores and fractures in rock may expand cause further cracking.

Glaciers also deposit rocky material creating even more features. Here’s a list of features formed by glacial deposition:

  1. Moraines – Terminal (at the snout of the glacier) Lateral (along the sides of the glacier) also outwash fans resulting from floodwater if the glaciers melt rapidly. Eskers (been to Esker in Ireland, the type locality) these are long sinuous ridges like railway embankments.
  2. Drumlins.
  3. Glacial till deposits.
  4. Kettle Holes depressions in glacial till caused by lumps of unmelted ice.
  5. Proglacial lake deposits. Lake deposits caused by a lake forming where a glacier forms a natural dam across a valley.

Ice-ages:
There is evidence for a large number of ice ages but the last one (which shaped Glendalough) is know as the Midlandian. It was punctuated by at least one mild phase around 65,000 to 35,000 years ago. During the last Ice Age, which ended approximately 10,000 years ago, 32 percent of Earth’s land area was covered with glaciers. At present, glaciers cover roughly 10 percent of the land area. A vast majority of that glacial ice overlies much of the continent of Antarctica. Most of the rest covers a great portion of Greenland; a small percentage is found in places such as Alaska, the Canadian Arctic, Patagonia, New Zealand, the Himalayan Mountains, and the Alps. The earlier ice age was called Munsterian which occurred between 300,000 and 130,000 years ago and was more extensive than the Midlandian.

The last Ice age in Ireland

The last Ice age in Ireland

Erratic:
Glacial erratic, a boulder picked up and transported by glacial ice. The rock type of the boulder differs from that of the underlying bedrock. The presence of erratics has always confused and enthralled humans.  In ancient times stories often developed attributing the strewing of erratic stones across the landscape to sprits or gods, and they may consequently have been used in monuments worshipping these.  Further through time, large stones or boulders, as well as other geological oddities, built up their own folklore, with stories of gods, devils, giants and witches, all explaining in various localities where and why elements in the landscape look as they do, as are where they are.  There are hundreds of beds where Diarmaid and Grainne lay throughout Ireland. Many of these are large erratic blocks.  We need not accept that these stories were generally believed, but such geological oddities certainly provided the basis for much story telling or seanchas.
Further through time, people in 19th Century Ireland always wondered why there were limestone gravels at 400m O.D. on the granite of the Wicklow Mountains (this after much advances had been made in the science of geology).
U-shaped valley
U-shaped valley is the shape left after a valley has been overdeepened by a glacier. The original V-shaped valley, which would have been made by a river, is widened and deepened after the ice has eroded the sides and bottom of the valley. V-shaped valleys have a wide flat floor, which may contain ribbon lakes. The sides of U-shaped valleys may have hanging valleys, which are side valleys that are left high on the side of a main valley that has been deepened by glaciation. Streams flowing in a hanging valley may form a waterfall as it flows down the steepened sides.

U-shaped valley diagram

U-shaped valley diagram

 

Ireland during last ice age

Ireland during last ice age

 

Features of glacial erratic

Features of glacial erratic

Field Results:
The cross section

We did 3 cross sections in total. I have put all 3 sets of results into a table (below).

1st Cross section
2nd Cross section
3rd Cross section of Break Slope
Distance from Start
Angles of slope
Distance from Start
Angles of slope
Distance from Start
Angles of Slope
10m
+2°
10m
+1°
20m
+3°
10m
+3°
10m
+4°
17m
+3°
10m
+2°
10m
+2°
20m
+6°
10m
+3°
10m
+5°
30m
+21°
10m
+5°
10m
+5°
18m
+22°
10m
+5°
10m
+4°
18m
+20°
10m
+20°
10m
+18°
22m
+24°
10m
+20°
10m
+21°
10m
+19°
10m
+20°
10m
+25°
10m
+23°
10m
+25°
10m
+26°
10m
+25°
10m
+20°
10m
+20°
10m
+21°
10m
+24°
10m
+24°
10m
+23°
10m
+24°

 

The table of results show clearly that Glendalough is a glaciated U-shaped valley which was made during the last ice age. While we did get the whole side done (because of the height) the diagram show a flat floor and the turn to form a U. One interesting thing is that the real world glaciated valleys are not as perfect as the ones in the geography book.

 

Sketch map:
The first task completed in the park was the sketch map. This was done at the gap between the upper and lower lake. The sketch shows clearly that Glendalough is a glaciated valley with a U-shape. Also the geological is clearly marked by vegetation.
Glacial Erratics:

We sets of measurements were by the class in Glendalough. There is the basic figure for height, length, breath.

Height
Length
Breath
5m
4m
1.2m
2.1m
4.4m
3m
5m
4.3m
1.5m

 

Glacial features on a map:

When we went to the park we took an OS map with us. We looked at it carefully and marked any glacial features we saw on it. These included a U-shaped valley, ribbon lakes and hanging valleys. I have drawn a sketch map from this and put it on the opposite page.

Conclusion

It is obvious from this project that Glendalough has been shaped by ice during the last ice age. My project showed how the park has features of glacial erosion and deposition.

 

Review:

Here is my review of the geography project. I think that I have achieved my aims:

  1. I investigated the glacial processes and landforms in general
  2. I drew a sketch map at the site,
  3. I did a cross section of the valley floor and got more information about the shape of the valley,
  4. I used an Ordnance Survey map to identify the glacial features in Glendalough National Park and worked out the directions that the glacial moved,
  5. I found out what is a glacial erratic and how they are formed,
  6. I discovered an example of an erratic in Glendalough,
  7. I studied the geology of the National Park and
  8. I found out about U-shaped valets and how they were formed by glaciers.

This was a worthwhile experience because I learnt a lot about the Glendalough national park as well as about glaciation, its processes and landforms. I also now have an understanding about how Glendalough national park was shaped by ice.

Sources:

Websites:

  1. www.google.ie
  2. http://www.irishtourist.com/details/wicklow_mountains_national_park.shtml