ST: Figure out the covered words.

Transcription

1 QU: Will this be a faultless lesson? AIM: To understand how lithology of a coastline can influence landforms and processes on a local scale ST: Figure out the covered words. 4 Dalmation or concordant 8 coastline eg. Dorset

2 Rocks, especially sedimentary rocks can contain many layers. These layers are termed as strata. In the photo below the strata is vertical and has been altered by plate movements. What might this mean for the erosion rates on this coast? Think what waves will do these gaps? The boundary between rock layers is called a 'bedding plane' COPY The angle/ dip and characteristics of rocks is referred to as lithology. 2

3 Cliff profiles??? Volunteer to leave the room while we draw around someones profile on the board. On return guess who it is. Draw profile here. 3

4 Cliff Profiles and their link to lithology. TASK: Below are 3 common cliff profiles created by their lithology draw each cross section but link the name and the correct description to it. EXT: On one of your diagrams label the bedding planes. Once finished complete the gap fill. (Next slide) Xsection Name Description Horizontal dip Landward dip Steep Seaward dip The profile is gentle as material can easily slide down the bedding planes making the cliff unstable & dangerous. Its profile is steep but the softer (lighter in colour) rock has undergone differential erosion producing notches. The notch creates overhangs prone to sudden collapse. A relatively steep profile with one or two overhangs produced by differential erosion. Rock fall is common. Gentle seaward dip A slightly reclined but still steep o o profile of 70 to 80. These cliffs are very stable as the strata dip means bedding planes are less exposed to wave erosion. 4

5 Cliff Profiles and their link to lithology. Rocks tend to form in layers of different rock types known as beds. These beds are subjected to tectonic forces that tilt and deform them so they dip at an angle. The angle the beds dip at affects how they are eroded and the profile of the resulting cliffs. These often lead to varied local scale changes in cliff profiles. Horizontal beds produce steep cliffs with notches where differential erosion has taken place. Near vertical beds (with a dip of ~90 ) also produce steep cliffs but differential erosion is less prevalent in these structures. Beds that dip seaward produce gentler cliffs but are less stable because loose material can slide down the bedding planes in mass movements. Landward dipping beds produce stabler & steeper cliffs. differential deform landward steep eroded beds seaward layers profile local Cliff Profiles and their link to lithology. Rocks tend to form in layers of different rock types known as beds. These beds are subjected to tectonic forces that tilt and deform them so they dip at an angle. The angle the beds dip at affects how they are eroded and the profile of the resulting cliffs. These often lead to varied local scale changes in cliff profiles. Horizontal beds produce steep cliffs with notches where differential erosion has taken place. Near vertical beds (with a dip of ~90 ) also produce steep cliffs but differential erosion is less prevalent in these structures. Beds that dip seaward produce gentler cliffs but are less stable because loose material can slide down the bedding planes in mass movements. Landward dipping beds produce stabler & steeper cliffs. differential deform landward steep eroded beds seaward layers profile local 5

6 Rocks tend to form in layers of different rock types known as beds. These beds are subjected to tectonic forces that tilt and deform them so they dip at an angle. The angle the beds dip at affects how they are eroded and the profile of the resulting cliffs. These often lead to varied local scale changes in cliff profiles. Horizontal beds produce steep cliffs with notches where differential erosion has taken place. Near vertical beds (with a dip of ~90 ) also produce steep cliffs but differential erosion is less prevalent in these structures. Beds that dip seaward produce gentler cliffs but are less stable because loose material can slide down the bedding planes in mass movements. Landward dipping beds produce stabler & steeper cliffs. The examples you have just sorted refer to strata which is still relatively intact with layers of rock overlaying each other...but rock can bend! 6

7 Tectonic forces can fold rocks into ANTICLINES and SYNCLINES. This alters their lithology and resistence to erosion. axis axis Fracture/Fault Volunteer to annotate features from the diagram above onto the photo below. LISTEN to the class discussion/answers to the questions below as you will need these key points for the next task. 1 are small cracks in rocks. Why do they widen in an anticline and close in a syncline? 2 What might this mean for vulnerability to weathering and erosion? 3 As the Anticline becomes more severe (overturns) what happens along the axis line? 4 What could this mean for weathering and erosion? 5 Why do landforms found locally differ so much in these areas? 7

8 LISTEN to the class discussion/answers to the questions below as you will need these key points for the next task. 1 are small cracks in rocks. Why do they widen in an anticline and close in a syncline? 2 What might this mean for vulnerability to weathering and erosion? 3 As the Anticline becomes more severe (overturns) what happens along the axis line? 4 What could this mean for weathering and erosion? 5 Why do landforms found locally differ so much in these areas? TASK: Stick in your version of the diagram below. Now answer the above in your own words. You were told to listen... axis axis Fracture/Fault Ext: Name/research on your phone the three general classifications of rock. Which occur in layers and which is the most resistent to erosion? 8

9 Folding Anticlines and Synclines axis axis Fracture/Fault Folding Anticlines and Synclines axis axis Fracture/Fault Folding Anticlines and Synclines axis axis Fracture/Fault Folding Anticlines and Synclines axis axis Fracture/Fault 9

10 And dictates what features can occur locally. 10

11 fissures enlargened by erosion Can you identify the micro features this has produced in this LOCALITY! Lets keep a sense of scale. 11

12 Be a twenty second expert. Call back a colour and talk the talk. Micro features 12

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