Slip or slump?

Slip or Slump

Valentines Day Massacre?

St Bees Coast 2011

Coastal Features

• Tomlin Head faces the West

• The Golf Course cliffs faces the west

• Between these a bay faces southwards and so takes the full force of the wind and waves

• Tomlin Head is made from younger Red sandstone

• The Golf course is made from loose debris

Slip or Slide?

SLOW

Carson = Kirkby

WET

DRY

FAST

Creep Slide

Slump

Obviously not a slow creep as the movement was rapid [overnight]

But was it a slip [dry]? or slump [wet]?

Notice the rounded ‘toe’

Notice the shapes [there were two movements]

Easternmost

Area of erosion

Mov

emen

t

toe

Cone shaped top

Westernmost

Can you identify the two distinct zones?

Why are they different colours?

Colour

Light

WET

DRY

Light

To the left you can see how saturated this is – 100 mm of rain has fallen in

the last two weeks

This makes it – Heavier, Lubricated, and created a junction – the shear plane

From the top you can see the two ‘toes’

Putting all of the evidence together-

SLOW

Carson = Kirkby

WET

DRY

FAST

Creep Slide

Slump

1. Saturated soil

2. Concave erosion and convex shape

3. Easily identifiable ‘toe’

So, the footpath is closed