LITHOSPHERE GLACIATION Lesley Monk Balfron High School Session

LITHOSPHERE GLACIATION Lesley Monk Balfron High School Session 2005/6 1

LITHOSPHERE deposition GLACIATION These slide-shows are all on the Prepwork folder if you wish to copy any notes from them; we will not be stopping in class for you to do this LANDFORMS OF GLACIAL DEPOSITION Materials carried by the glaciers are deposited in two main ways; v. Glacial Deposits (unsorted) and v. Fluvio-glacial deposits (sorted) In the booklet, read the section about this and also the different types of moraine. 2

LITHOSPHERE deposition GLACIATION Ø Moraine is the waste material worn away and collected by the ice. ØIt is angular in shape. ØGlacial deposits are poorly sorted, ie all different sizes and rock types are mixed together. 3

LITHOSPHERE deposition GLACIATION See the moraine on the glacier surface. 4

LITHOSPHERE deposition GLACIATION TYPES OF MORAINE Lateral moraine is found on the sides of the glacier. Scree, from frost shattering, is an important source. Ground moraine is found at the base (bottom) of the ice. It is also called till or boulder clay. Supra-glacial Englacial moraine is found inside the ice itself. Medial moraine is found down the middle of the glacial surface and occurs when the inner lateral moraines of two glaciers join. Terminal moraine is found in front of the snout of the glacier if it is stationary. It represents the maximum advance of the ice. 5

LITHOSPHERE deposition GLACIATION 15 There is a handout of this for your jotter! 6

LITHOSPHERE Terminal moraine deposition GLACIATION Snout of glacier 7

LITHOSPHERE deposition GLACIATION Read the booklet- factzone 15 page 37 - and answer these questions; Q 1. In the diagram, in which direction was the glacier flowing? A. From east towards the west. Q 2. What is the difference between ablation till and lodgement till? A. Ablation till was formed as the ice melted; the moraine was lowered to the valley floor as the ice thinned and wasted away. Lodgement till was created in situ, as the ice ground along the valley floor. 8

LITHOSPHERE deposition GLACIATION Q 3. From which two places is terminal moraine delivered to the snout? A. From the subglacial moraine below the ice, bulldozed in front of the ice, and from supraglacial moraine being transported along the ice surface to the snout. Q 4. If, after retreating back up the valley, a glacier starts back down for a short time in a cold spell; what is formed and why is it small? A. This recessional moraine is like a terminal, but has less material bulldozed in front; therefore it is smaller. The next slides illustrate depositional features described in your booklet. Read them carefully! 9

LITHOSPHERE ERRATICS deposition GLACIATION Erratics are large rocks that are completely different from the type of rocks on which they rest They were carried by the ice-sheet, sometimes for hundreds of kilometres and then deposited. 10

LITHOSPHERE deposition GLACIATION Erratics like this are often found on the valley floor. 11

LITHOSPHERE deposition GLACIATION ESKER Glacial streams are found under the ice. They are loaded with debris (sand gravel) carried by the meltwater. As the ice retreats, the river deposits load. The built-up river bed is called an Esker. This river has all but dried up! 12

LITHOSPHERE deposition GLACIATION An esker is a steep-sided, long, winding ridge, made up of gravel and sand. Most are tree-covered. 13

LITHOSPHERE DRUMLIN Drumlins are smooth, rounded mounds of ground moraine. The steep (stoss) side faces the direction the ice Moved from. Drumlins often occur in swarms or groups on the valley floor. deposition GLACIATION Side view Plan view 14

LITHOSPHERE deposition GLACIATION Here is a drumlin outside Buchlyvie. Can you work out the ice direction? 15

LITHOSPHERE deposition GLACIATION Meltwater streams bringing outwash to be distributed across an outwash plain. Note the braiding of the stream channels. 16

LITHOSPHERE deposition GLACIATION A KETTLEHOLE LAKE Can you name the two Scottish examples we learned about in S Grade? LOCH MORLICH LAKE OF MENTEITH depression formed when ice melts depression filled with water to form kettle lake 17

LITHOSPHERE deposition GLACIATION What is a kame terrace? GLACIER Once the ice has melted, the debris has been lowered to the valley floor and created a terrace with a steep side and flattish top. During the end stages of glaciation, a lake gathers at each side of the ice, filling with moraine. Kame terraces 18

LITHOSPHERE deposition GLACIATION This slide shows a set of kame terraces. 19

LITHOSPHERE deposition GLACIATION Identify the features shown on the diagram by matching the numbers to the names given. Esker / Terminal Moraine / Outwash Plain / Drumlin / Till (Ground Moraine/Boulder Clay) / Kettlehole lake / Outwash Sands and Gravels. 20

LITHOSPHERE deposition GLACIATION As you go through your revision, for each feature mentioned, look back through your textbooks and this presentation. You are looking for named examples of as many features as possible. Remember that you will get marks in the exam and NAB’s for showing the skill of quoting places as examples from your notes! 21

LITHOSPHERE deposition GLACIATION CONGRATULATIONS! YOU HAVE NOW COMPLETED YOUR LITHOSPHERE UNIT. 22