ISOSTATIC ICE Isostatic local Isostatic sea level change can be attributed to the wait of ice. And is a local change because the ice only covers a local area. Added for recap purposes

Eustatic YOU STATIC change – caused by you as you cause global warming which cause ice cap melt which adds water to the see.

Josh Killengray and Beren Miles March 2015 G3.2.C Mass Movement Handouts to go with this PowerPoint: - Slides 13+14 on a notes/slides 3 per pages print out - Mass Movement Handout Mass Movement rotational slip case study on Barton on sea Josh Killengray and Beren Miles March 2015

Aims To have a valid definition of Mass Movement To have a detailed understanding of Mass Movement and to know about different processes of Mass Movement. To have a developed a Case Study on Mass Movement Quickly go through aims of the lesson, so that students know what they need to get out of the lesson.

Definition Weathered Material – The cliff (rock, soil, plant materials) Mass movement is a Sub-aerial Process that affects the shape of the coastline. It is the downhill movement of all weathered material (regolith), including soil, loose stones and rocks, in response to the force of gravity. It includes the processes such as: rock falls, landslides, Mudflows, rotational slips and soil creep. Get students to come up with there own definition on there tables: Give them 3 minutes then feedback from each table. Then put my definition on the board and give around the handout sheet. Gravity is a key word within this definition: in most cases if gravity is not referred to then you wont get the mark! However, it excludes movement where the material is carried by ice, water or wind.

This makes the cliff unstable and prone to collapse. Mass Movement is common at the coast because of the constant undercutting of the cliffs by the sea. This makes the cliff unstable and prone to collapse. Weathering also leads to Mass Movement When the cliff becomes unstable there is a downhill movement of all the weathered material due to the force of gravity (This is on the hand out)

Classification Rock Falls Landslides/Rotational slip/Slumping Mudflows High Rock Falls Landslides/Rotational slip/Slumping Mudflows Runoff Soil Creep Solifluction Flow Water Content Get students to guess where the processes go on the triangle Then show the finished article. slide Heave Low Slow Speed of Movement Fast

Classification Asked students to copy this onto the uncompleted one on there handout

Rockfalls Material, once broken from the surface, will either bounce or fall vertically to form scree, or talus, at the foot of a slope. Rock fall is the rapid, free-fall of rock from a steep cliff face. Rock fragments fall from the face of the cliff because of the action of gravity. This is made worse by freeze-thaw action loosening the rock. Bare, well-jointed rock is very vulnerable to rock fall - water enters the joint, freezes and expands, cracking the rock. A scree slope of fallen rock is formed at the bottom of the cliff. They may result from extreme physical or chemical weathering, pressure release, or storm-wave action. On the handout Students should highlight key words on there handout

Rock Fall at Burton Bradstock (West Dorset)

Slides, slumps and slips Landslips or land slumps are occasional, rapid movements of a mass of earth or rock sliding along a concave plane. They can occur after periods of heavy rain, when the water saturates overlying rock, making it heavy and liable to slide. Undercutting of a steep slope by river or sea erosion weakens the rock above, also making a slump likely. Slides Largely retain their internal structure and move as a large mass. Slumps Occur where the movement appears to have a rotational element Cliffs formed of impermeable rocks such as clays are susceptible to rotational slumping after rainfall. The fundamental difference between slides and flows is that flows suffer internal derangement whilst, in contrast, slides move ‘en masse’ and are not affected by internal derangement. On the handout Students should highlight key words on there handout

Slides may be planar or rotational. In a planar, the weathered rock moves downhill leaving behind it a flat rupture surface. Where rotational movement occurs, a process sometimes referred to as slumping, a curved rupture surface is produced. On the handout Students should highlight key words on there handout

Soil creep is a very slow movement, occurring on very gentle slopes because of the way soil particles repeatedly expand and contract in wet and dry periods. When wet, soil particles increase in size and weight, and expand at right angles. When the soil dries out, it contracts vertically. As a result, the soil slowly moves downslope. Mudflow occurs on steep slopes over 10°. It's a rapid sudden movement which occurs after periods of heavy rain. When there is not enough vegetation to hold the soil in place, saturated soil flows over impermeable sub soil, causing great devastation and endangering lives. Slides 13 and 14 should be printed in a notes format and given to students so they can make notes alongside them as we go through each process

Solifluction occurs mainly in tundra areas where soils are often frozen for around nine months of the year and where vegetation is sparse. When the topsoils that in the summer the additional water and lack of vegetation leads to a active flowing layer. Runoff has the ability to move fine material downslope particularly where overland flow occurs as a thin continuous layer and washes slit and clay sized particles.

Practice Questions Define the term ‘mass movement’.(2 marks) Describe evidence (in Figure 3) which shows that mass movement has occurred. (4 Marks) Discuss the relative importance of two or more processes responsible for shaping the coast (such as marine erosion, transportation; deposition and land-based sub-aerial weathering, mass movement and runoff). (15 Marks) Go through these practice questions with the students if time allows 3 (a) (i) AO1 – 2 Mass movement involves the shifting downslope under the influence of gravity of unconsolidated material/rocks/weathered material as a unit at varying speeds – from very fast such as falls to very slow, such as creep. Two examples of mass movement is worth one mark. 2×1 (2 marks) 3 (a) (ii) AO1 – 1, AO2 – 1, AO3 – 2 Slumping is likely to be recognised. There is much material at the base of the cliffs. This appears to be loose material and links in the foreground to areas of shift at the top of the cliffs / jagged edges. Here a ‘line’ of movement is visible, especially at the very top, where the material has shifted in a plane as a unit. Slip plane is covered as material has slumped down. The vegetation has shifted with it and is incomplete. The lack of vegetation lower down the slopes is indicative of instability. 4x1