WJEC – Geology of the Human Environment (GL3) – May 2002
1.
Figure 1a shows a map and Figure 1b shows a section of the location and geology of
the ancient Taren Landslip in South Wales.
After ‘Routeway’ ESTA, Science of the Earth.
Figure 1b
Refer to Figure 1a and 1b.
(a)
The section shows that the landslip toe covers glacial deposits.
What does this indicate about the relative age of the landslip?
[1]
……………….………………………………………………………………………………….
(b)
State and explain two geological factors that may have been responsible for the
Taren Landslip.
[4]
Factor 1……………..……………………………………….………………………….
Explanation………………………………………………….………………………….
………………………………………………………………………………………….
Factor 2……………….…………………………………….………………………….
Explanation…………………….………………………………………………………..
………………………………………………………………………………………….
(c)
Figure 1b shows that the new road was constructed across the toe of the Taren
Landslip, parts of which are moving at a few millimetres per year.
Explain how the following engineering solutions have helped with slope
stabilisation:
(i)
the drainage tunnel at Y;
[2]
……………………………………………………………………...……………………………
………………………..………………………………………………………………………….
…………………………………………………………………………………………………...
(ii)
the embankment at X .
[2]
…………………………………………………………………………………………………..
…………………………………………………………………………………………………..
……..……………………………………………………………………………..……………..
(iii)
Explain how the river might affect the long-stability of the
Taren Landslip.
[3]
…………………………………………………………………………………………………..
…………………………………………………………………………………………………..
……..……………………………………………………………………………..……………..
…………………………………………………………………………………………………..
……..……………………………………………………………………………..……………..
Total 12 marks.
Notes for answers
These represent suggested answers and do not necessarily represent all the possible
acceptable alternatives of a mark scheme.
Question 1
(a)
Landslip younger than glacial deposits/last 10,000 years.
(b)
Explanation may include:
Angle of slope (oversteepened valley side),
Downslope dip
Lithology (impermeable and/or weak shale/coal layers, permeable sandstones)
Reference to heavy rain on sequence,
Post-glacial melting of permafrost,
Groundwater regime,
Weathering, load,
Shrinkage/expansion,
Ground vibration,
Presence of fault.
(2 for each explained)
[4]
(c)
(i)
(ii)
(iii)
[1]
Drain water from slip
Reduce pore pressure at slip surface
Other sensible
(2 max)
[2]
Increased weight/support for slip toe
Prevent further movement/prevent erosion
Other sensible
(2 max)
[2]
Meandering river - will change its course
Toe removal by erosion increases instability - no support
River levels may rise - flooding & increase saturation/erosion
Increase saturation - instability from lubrication/soil flow
Other sensible
(3 max)
[3]
Total 12 marks
ESTA would like to thank the WJEC for allowing this question to be published on GEOTREX.
Any comments should be directed to the Subject Officer for Geology at the WJEC 15/04/2007