Lesley Monk Balfron High School Session 2005/6

LANDFORMS OF GLACIAL DEPOSITION 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; Glacial Deposits (unsorted) and Fluvio-glacial deposits (sorted) In the booklet, read the section about this and also the different types of moraine.

deposition It is angular in shape. Moraine is the waste material worn away and collected by the ice. It is angular in shape. Glacial deposits are poorly sorted, ie all different sizes and rock types are mixed together.

deposition See the moraine on the glacier surface.

deposition 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.

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

deposition Terminal moraine Snout of glacier

deposition Read the booklet- factzone 15 page 37 - and answer these questions;- Q1. In the diagram, in which direction was the glacier flowing? A. From east towards the west. Q2. 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.

deposition Q3.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. Q4. 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!

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

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

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

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

deposition DRUMLIN Side view 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. Plan view

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

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

Can you name the two Scottish examples we learned about in S Grade? deposition 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

deposition What is a kame terrace? During the end stages of glaciation, a lake gathers at each side of the ice, filling with moraine. 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. Kame terraces

deposition This slide shows a set of kame terraces.

Identify the features shown on the diagram by matching deposition 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.

deposition 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!

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