GCR volume 33. Tables

(Table 1.1)

(a) Hutchinson's classification of mass movements on slopes (1968a)

Creep	(1) Shallow, predominantly seasonal creep
	(a) Soil creep
	(b) Talus creep
	(2) Deep-seated continuous creep; mass creep
	(3) Progressive creep

Frozen ground	(4) Freeze—thaw movements
	(a) Solifluction
	(b) Cambering and valley-bulging
	(c) Stone streams
	(d) Rock glaciers
Landslides	(5) Translational slides
	(a) Rock slides; block glides
	(b) Slab, or flake slides
	(c) Detritus, or debris slides
	(d) Mudflows
	(i) Climatic mudflows
	(ii) Volcanic mudflows
	(e) Bog flows; bog bursts
	(f) Flow failures
	(i) Loess flows
	(ii) Flow slides
	(6) Rotational slips
	(a) Single rotational slips
	(b) Multiple rotational slips
	(i) in stiff, fissured clay
	(ii) in soft, extra-sensitive clays; clay flows
	(c) Successive, or stepped rotational slips
	(7) Falls
	(a) Stone and boulder falls
	(b) Rock and soil falls

	(8) Sub-aqueous slides
	(a) Flow slides
	(b) Under-consolidated clay slides

(b) Hutchinson's (1988) classification (first two levels only).

A	Rebound
		1	Movements associated with man-made excavations
		2	Movements associated with naturally eroded valleys
B	Creep
		1	Superficial, predominantly seasonal creep; mantle creep
		2	Deep-seated, continuous creep; mass creep
		3	Pre-failure creep; progressive creep
		4	Post-failure creep
C	Sagging		of mountain slopes
		1	Single-sided sagging associated with the initial stages of landsliding
		2	Double-sided sagging, associated with the initial stages of double landsliding, leading to ridge spreading
		3	Sagging associated with multiple toppling
D	Landslides
		1	Confined failures
		2	Rotational slips
		3	Compound failures (markedly non-circular, with listric or bi-planar slip)
		4	Translational slides
E	Debris movements of flow-like form
		1	Mudslides (non-periglacial)
		2	Periglacial mudslides (gelifluction of clays)
		3	Flow slides
		4	Debris flows, very to extremely rapid flows of wet debris
		5	Sturzstroms, extremely rapid flows of dry debris
F	Topples
		1	Topples bounded by pre-existing discontinuities
		2	Topples released by tension failure at rear of mass
G	Falls
		1	Primary, involving fresh detachment of material; rock and soil falls
		2	Secondary, involving loose material, detached earlier; stone falls
H	Complex slope movements
		1	Cambering and valley-bulging
		2	Block-type slope movements
		3	Abandoned clay cliffs
		4	Landslides breaking down into mudslides or flows at the toe
		5	Slides caused by seepage erosion
		6	Multi-tiered slides
		7	Multi-storeyed slides

(Table 1.2) The candidate mass-movement GCR sites suggested by the panel of experts consulted in the 1980s.

Southern England	English Midlands	Northern England	Wales	Scotland
Axminster	Alport Castles	Askrigg	Aberfan–Cilfynydd	An Teallach
Axmouth–Lyme Regis	Bredon Hill	Bilsdale	Black Mountains	Arran north coast
Bath University	Bretton Clough	Birdsall	Blorenge	Arrochar
Beachy Head	Charlesworth	Buckland's Windypit	Bodafon Mountain	Beinn a'Ghlo
Black Ven	Crowden	Canyards Hills	Cefn-y-Gader	Beinn Alligin
Blacknor Cliffs	Deer Holes	Castle Eden Dene	Craig Cerig Gleisiad	Ben Attow (Beinn Fhada)
Brighton–Saltdean	Golden Valley, Chalford	Cautley Spout	Cwmystwyth	Ben Lawers
Chale Bay cliffs	Grindesgrain Tor	Dee, Wirral	Llangollen screes	Ben Tianavaig
Charmouth foreshore	Heyden Brook	Farndale	Llyn-y-Fan Fach	Ben Wyvis
Clovelly	Hob's House	Fremington Edge	Nant Gareg-Iwyd	Braeriach
Folkestone Warren	Jackfield	Gordale screes	Ponterwyd	Castle Ewen
Golden Cap	Lockerbrook Heights	Hilbeck Fell	Tal-y-Llyn valley	Cnoc Roll
Hadleigh	Longdendale	Holderness coast	Taren-y-Gigfran	Coire Gabhail
Herne Bay	Lud's Church	Kettleness, Staithes	Ysgyryd Fawr	Cuillin screes
High Halstow	Mam Tor	Lake District screes		Drumochter Pass
Hog's Back cliffs	Norfolk Coast	Malham		Eigg
Hooken Cliff, Beer	Northants ironstone field	Marske		Gleann an Dubh-Lochain
Hythe-Lympne-Aldington	Peter's Rock	Peak Scar		Glen Pean
Kent and Sussex Chalk cliffs	Postlip Warren	Rosedale		Glen Tilt
Keynsham railway cutting	Rockingham	Rowlee Pasture		Gribun, Mull
Maidstone cambering	Stow-on-the-Wold	Runswick Bay		Jura
Oaken Wood, Medway	The Wonder	Scarborough		Lairig Ghru
Osmington	Westend Valley	Speeton Bay		Loch Teachuis
Sevenoaks bypass	Wytham Hill	Teesdale		Lochnagar
Spot Lane, Maidstone		Wakerley		Quiraing
Stonebarrow		Whitestone Cliff		Hallaig, Raasay _
Ventnor Undercliff				Rudha Gorhhaig
Warden Point				St Kilda
Winterford Heath				Storr
				Streap
				Tinto Hills

(Table 1.3) The final list of selected mass-movement sites as drawn up in the early 1980s.

Alport Castles, Derbyshire

Axmouth-Lyme Regis, Devon–Dorset

Beinn Fhada, Highland

Black Ven, Dorset

Blacknor Cliffs, Dorset

Buckland's Windypit,

North Yorkshire

Canyards Hills, Sheffield

Coire Gabhail, Highland

Eglwyseg Scarp (Creigiau Eglwyseg), Clwyd

Entrance Cutting at Bath University, Avon

Cwm-du, Ceredigion

Folkestone Warren, Kent

Glen Pean, Highland* Hallaig,

Isle of Raasay, Highland

High Halstow, Kent

Hob's House, Derbyshire

Llyn-y-Fan Fach, Carmarthenshire

Lud's Church, North Staffordshire

Mam Tor, Derbyshire

Peak Scar, North Yorkshire

Postlip Warren, Gloucestershire

Rowlee Bridge, Derbyshire

Spot Lane Quarry, Kent*

Stutfall Castle, Kent

Trimingham Cliffs, Norfolk

Trotternish Escarpment, Isle of Skye, Highland (The Storr and Quiraing)

Warden Point, Kent

* Glen Pean and Spot Lane Quarry have now been deleted from the Mass-Movements GCR 'Block' (selection category) — see text.

(Table 1.4) The supplementary sites added to the GCR following recent research in Scotland.

Beinn Alligin, Highland

Ben Hee, Highland

Benvane (Beinn Bhàn), Stirling

Carn Dubh, Ben Gulabin, Perthshire

The Cobbler (Beinn Artair), Argyll and Bute

Druim Shionnach, Highland

Glen Ample, Stirling

Sgurr na Ciste Duibhe, Highland

The mass-movement GCR sites described in the present volume; style and type are according to the World Landslide Inventory (WP/WLI 1993), classifications are according to Hutchinson (1968a) and (1988) — described in (Table 1.1)a,b.

Site	Authors' classifications	Style	Type	Hutchinson categories 1968a	Hutchinson categories 1988
Alport Castles	Mass rock creep, retrogressive rotational, translational	Composite	Slide, flow	2, 5a, 6bi	B2, D2, D4
Axmouth-Lyme Regis	Translational, rotational, subsidence	Complex	Slide, spread	5a, 6bi, 6a, 6c, 7a, 7b	D2, D3, D4
Beinn Fhada (Ben Attow)	Large-scale slope deformation, local slides, possible sags or forward topples	Complex	Spread	2, 5a	A2, B2, Cl, D4, Fl
Beinn Alligin	Large rockfall with excess run-out	Single	Fall, flow	5fii, 7b	E3, G1
Ben Hee	Arrested translational slide	Multiple	Slide	5a	D4
Benvane	Slope deformation and translational slide	Multiple	Spread, slide	2, 5a	B2, D4
Black Ven	Mudslides	Complex	Slide	5di	El
Blacknor Cliffs	Block slide, slab failure	Complex	Slide, topple	5a	D4
Buckland's Windypit	Block slides	Multiple	Slide	5a, 4b	D4
Canyards Hills	Translational with breakup into ridges, lateral extension	Multiple	Slide	5a	D4
Carn Dubh, Ben Gulabin	Translational slide to flow	Single	Slide, flow	5a, 5fii	D4, E4
Coire Gabhail	Rockfalls, landslide dam, run-up opposite	Multiple	Fall	7b	G1
Cwm-du	Sub-snow solifluction sheets OR 'landslides'	Multiple	Slide	4a, 5c	E2
Druim Shionnach	In-situ slope deformation progressing to toppling	Composite	Spread	2	B2, C3
Eglwyseg Scarp (Creigiau Eglwyseg)	Active screes and relict clitter slopes	Multiple	Fall	7a, 7b	G
Entrance Cutting at Bath University	Gulls, cambers, dip-and-fault structure	Composite	Spread	4b	H
Folkestone Warren	Rockfalls, clay extrusion, rotational	Complex	Fall, slide	6bi	D2, G, H
Hallaig	Rotational slide, possibly seismically triggered	Single	Slide	6a	D2
Glen Ample
Beinn Each	Compressional slope deformation, local rockfall	Multiple	Spread	2, 7b	A2, G1
Ben Our	Extensional slope deformation, slides, topples	Complex	Spread	2, 5a	B2, C1, D4, F1
High Halstow	Shallow successive rotational slips, hillwash, soil creep	Successive	Slide	la, 6bi, 6c	B, D2
Hob's House	Rotational slip	Single	Slide	6a	D2
Llyn-y-Fan Each	Debris flow	Multiple	Flow	5c	E3
Lud's Church	Bed-on-bed translational sliding within a rotational mass	Single	Slide	5a, 6a	D2, D4
Mam Tor	Slump-earthflow	Multiple	Slide, flow	6c, 5c	D3, E3, H4
Peak Scar	Block slide, topples	Complex	Slide, topple	5a	D4, F
Postlip Warren	Large-scale gravitational slips, 'founders'	Successive	Spread	5a, 4b	H
Rowlee Bridge	Valley-bulge	Complex	Spread	4b	H
Sgurr na Ciste Duibhe	Extensional slope deformations and slides	Complex	Spread, slide	2, 5a	B2, D4
Stutfall Castle	Soil creep, earthflow, translational	Complex	Flow, slide	la, 5c, 6b	B, D4, E1
The Cobbler	'Short-travel arrested translational slide; also sub- cataclasmic	Single	Slide, fall	5a, 7b	D4, E3
Trimingham Cliffs	Blockfall, seepage failure, mudslides, rotational slip	Composite	Fall, slide	5di, 6a	D2, El, G, H
Trotternish Escarpment
Quiraing	Retrogressive translational slide, rockfall	Multiple	Slide, fall	5a, 7b	D4, G1
The Storr	Retrogressive translational slide, topples	Multiple	Slide, topple	5a, 7b	D4, F2
Warden Point	Rotational, topples	Composite	Slide, topple	6b	D2, F

(Table 1.6) The sites described in the present volume classified by geological age and by WLI mass-movement type: (PC = Precambrian–Cambrian; Si = Silurian; De = Devonian; Ca = Carboniferous; Ju = Jurassic; Cr = Cretaceous; Eo = London Clay; PI = Pleistocene; fa = fall; to = Topple; sl = slide; sp = spread; fl = flow; * = sites which display cambering and valley-bulging).

Geological age

Mass-movement type

Alport Castles

Axmouth–Lyme Regis

Beinn Alligin

Beinn Fhada *

Ben Hee

Benvane

Black Ven

Blacknor Cliffs

Buckland's Windypit

Canyards Hills

Carn Dubh, Ben Gulabin

ICoire Gabhail

Cwm-du

Druim Shionnach *

Eglwyseg Scarp (Creigiau Eglwyseg)

Entrance Cutting at Bath University *

Folkestone Warren

Glen Ample

Beinn Each *

Ben Our

Hallaig

High Halstow

Hob's House

Llyn-y-Fan Each

Lud's Church

Mam Tor

Peak Scar

Postlip Warren

Rowlee Bridge *

Sgurr na Ciste Duibhe

Stutfall Castle

The Cobbler

Trimingham Cliffs

Trotternish Escarpment

Quiraing

The Storr

Warden Point

(Table 2.1) Characteristic types of large rock slope failures (RSFs) in the Scottish Highlands and Lake District. Adapted from Jarman (2006) and Wilson et al. (2004). See (Figure 2.5) for explanation of terms.

		Scottish Highlands	Lake District
RSF size	0.25–0.49 km²	67	5
	0.5–0.99 km²	61	1
	1.0–1.99 km²	16	1
	2.0–3.0 km²	3	—
total RSFs	0.25–3.0 km²	147	7

RSF predominant mode
rockslides (all degrees of arrestment/disintegration)		54	4
of which	cataclasmic	3	—
	sub-cataclasmic	14	—
	arrested short-medium travel	37	4
slope deformations		92	3
of which	extensional (sag and creep)	68	3
of which	compressional (rebound) including Cluanie hybrids	24	—

Association with glacial breaches (including tributary troughs)
	main watersheds	55	1
	secondary watersheds	56	1
	no close association	36	5

(Table 2.2) Rock slope failure (RSF) incidence, character, landshaping effect, and association with breaching in the Southern Highlands and Kintail area (including clusters 1, 5 and 7 in (Figure 2.13)). Updated from Jarman (2003a,b). Note: sites may be in more than one character or landshaping category. See (Figure 2.15) and (Figure 2.18).

		Southern Highlands			S. Affric/Kintail/Glen Shiel
	1W	1E	2	Total	7N/8S
Number of RSFs	119	40	13	172	54
< 0.25 km²	86	33	8	127	33
0.25–0.99 km²	31	6	4	41	17
1.00–3.00 km²	2	1	1	4	4

Extent of RSF (km²)	27.9	7.0	5.2	40.1	18.6
average size (km²)	0.23	0.17	0.40		0.35
% of densest core area affected by RSF	7.7	7.2	16.7		6.0
extent of core area (km²)	112	40	26		41

RSF character (number of)
arrested translational slides	48	20	11	79	25
sub-cataclasmic failures	35	21	6	62	6
slope deformations	6	10	5	21	23
incipient failures	28	10	5	43	5
not ascertained	26	8	1	35	—

Landshaping contribution
glen and trough widening	89	17	9	115	38
corrie enlargement	13	13	1	27	11
corrie initiation	11	2	1	14	—
spur truncation	39	11	6	56	9
crest sharpening, arêtes and horns	39	16	7	62	19
ridge reduction	8	5	0	13	23
potential watershed breaching/ dissection	3	2	2	7	6
elimination of mountain blocks	12	4	1	17	2

Association with evolving glacial breaches
at a 'recent' or enlarging breach	20	5	5	30	27
near a breach (< 2 km downflow)	24	15	4	43
in a side trough rejuvenated by a breach below					11

(Table 2.3) Large rock slope failures (RSFs) in the Scottish Highlands for which data are available. After Jarman (2006). Sites are listed from the north, with the Great Glen separating the North-west Highlands from the Grampians. Note the disproportionate number of large RSFs studied north-west of the Great Glen, where foliation (F) is rarely as conducive to sliding as in the Southern Highlands. Most studies are of (sub-)cataclasmic RSFs or slope deformations, rather than conventional arrested slides.

RSF	Ref.	Mode	Area km²	Vol. x106m³	Depth m	H/S m	A/S m	Slide plane	Comments
Loch Vaich, Ross-shire	2	ext def	0.5		>50?		2	J low angle	Short-travel (50 m) slip, forward toppling on 60° F
Sgurr Bhreac, Fannich	2,3	ext def	0.82	36?	?	30	Sm	?	Sackung with lattice of fissures
Beinn Alligin, Torridon	1,2	cata	0.52	3.5	200 20 #1	60	—	42°	Acute faulted wedge in sub-horizontal sandstone
Glenuaig, Strathcarron	2	ext def	0.7		?	<5	<2	F 15°+	Short-travel sliding slump, incipient fissuring
Sgurr na Conbhaire, Monar	2,6	sub-cata	0.35		150		2	F 30- 40°	Long-travel (150 m) slump onto lower slope
Sgurr na Feartaig, Strathcarron	2	ext def	0.9		100?	2	yes	F	Short-travel block slide
An Socach, Monar	2	comp def	1.0	—	20?	nil	sm	-	500 m long, linear A/S diffuse margins — rebound
Carn na Con Dhu, Mullardoch	2,3	slide	1.46	61?	120?	12 35?	2	not on F/J	Short-travel slide/slump, A/S <200 m long on strike of J1+J2
An Sornach, Affric	2,3,4	ext def	0.75	13?	30?	42	3	not F/J	Slip with A/S lattice > bulge > collapse. Rebound 5 m A/S
Mullach Fraoch-choire, Affric	3	sub-cata	0.2	0.73	20	10	—	J2,3 29°	Slide tongue within 1.1 km' slope deformation
Sgurr na Lapaich, Affric	2,3	comp def	0.3	7?	100?	10	—	—	Ridge crest failure, possibly seismic/rebound faulting
Beinn Fhada, Kintail	2,3, 4,6	comp def	3.0	112 #2	100?	none	10	—	~8 sub-horizontal A/S < 700 m long, main ones are 5–8 m high
Sgurr na Ciste Duibhe, Glenshiel	5	ext def	1.25	5–10 #3	80	15	(11) 5	not F/J	Summit lowered -10 m > long-travel slide in deformation
Sgurr a' Bhealaich Dheirg, Glenshiel	2	comp def	0.7		100?		6	—	Bulging slide, rebound A/S < 200 m long
Ciste Dhubh, Affric	5	sub-cata	0.46	7	80	30	2	?	Corrie-floor source, toe reaches river in breach glen
Druim Shionnach, Cluanie	5	comp def	0.55	—	150?	25	(14) 3	—	Top A/S is outer half of graben > Cluanie bulge
Meall Buidhe, Knoydart	6	ext def	0.5		40?	30	7?	J1,2 < 44°	Broad slump zone
Mam na Cloiche Airde, Knoydart	6	sub-cata	0.26		40	20	—	35°	Semi-intact masses > slope debris > 5° flow slide
Glen Pean, Knoydart	6	comp def	2.5	—	60?		—	J1 28–48°	A/S array on strike of F/J2, cataclasmic slide to west
Great Glen
Streap, Glenfinnan	6	Slide	0.25		25	75	(10)	J1 36°	Long-travel arrested sub-cataclasmic summit has lost top ~15 m, seismic trigger?
Beinn an Lochain W, Arrochar	6	ext def	0.34		15?	<5	<2	F 20–30°	Thin, undeveloped slide, upper tier beside
The Cobbler SW, Arrochar	4	slide	0.62	8–10	30	28	(10) 6	not F	Four-panel, short-travel, disintegrated slip
Hell's Glen, Cowal	3,6	ext def	0.52	1.75 (+)	60	15	(15) 5	J2 40–50°	Topple block slips and collapses in broad slump
Mullach Coire a' Chuir, Cowal	3	slide	0.57	9.6?	20	50	(12) 2	F + J2	Part-collapsed sliding topple on stepped surface
Meallan Sidhein, Loch Striven	6	slide	0.75		70	40	—	F 25–32°	Slip in phyllite, effective F dip 20°, equals RFA
Tullich Hill West and East	4	slide	1.25 in total			40	8	not F	Short-travel, multi-phase, slump complex
Benvane, Trossachs	4	def/ slide	1.25	25	20–30	26	3	not F	Deformation progresses laterally to slide
Ben Our (Glen Ample), Lochearnhead	4	def	2.90	100–200?	150?	4	4	—	Platy deformation with basal slumps
Footnotes: 'Ref.': reference sources are (1) Ballantyne, 2003; (2) Fenton, 1991; (3) Holmes, 1984; (4) Jarman, 2003c,d,e, 2004a, and present volume; (5) Jarman, 2003b; (6) Watters, 1972. 'Mode': cata = cataclasmic; sub-cata = sub-cataclasmic; ext def = extensional deformation (sag, creep); comp def = compressional deformation (rebound). 'Area': RSF size is here taken as the gross area including source cavity, since most cases are incompletely evacuated. British Geological Survey mapping of RSF is variable and incomplete, but recent sheets only map as 'landslips' disturbed ground, thus excluding both source areas and semi-intact slope deformations. The gross area best indicates the geomorphologi-cal impact of the RSF, but clearly requires adjustment when volumetric calculations are made. 'Vol'(-ume) and maximum 'Depth' should be seen as broad estimates, especially sites marked '?' where the depth cannot readily be assessed. #1 depth figures are for cavity (ref. 2) and debris tongue (ref. 1); #2 volume (ref. 3) assumes there is a failed mass with a boundary at -100 m, no volume can be calculated if the failure partly dissipates at depth; #3 volume and depth are for main cavity within larger deformation. 'H/S' = headscarp (rear scarp, source scarp) maximum height. 'A/S' = antiscarp (obsequent scarp, counterscarp, uphill-facing scarp) maximum height — figures in brackets are graben trenches or uphill faces of large slipped masses. 'Slide plane': F = foliation or schistosity surface; J = joint-sets (in order of significance); RFA = residual friction angle.

(Table 5.1) Records of movement and rainfall at Mam Tor, 1915–1977. After Skempton et al. (1989).

Slip	Date	Movements	Monthly rainfall (mm)
1	Jan 1915	Crack 30 m long	200
2	Dec 1918	slip, 0.3 m subsidence	240
	Jan 1919	movements continue	140
3	Dec 1919	steady movement	280
	Jan 1920	movements continue	200
4	Dec 1929	serious slip	300
	Jan 1930	movements continue	180
5	Jan 1931	slip, 60 m crack	210
	Feb 1931	movements continue	190
6	Feb 1937	considerable subsidence	220
7	Jan 1939	100 m crack, 0.25 m subsidence	210
8	Oct 1942	30 m crack, 0.1 m subsidence	160
9	Feb 1946	extensive slip	240
10	Nov 1946	new movements	230
11	Feb 1948	subsidence on 200 m length (preceded by 280 mm rain in Jan)	100
12	Dec 1949	slip (no details)	230
13	Jan 1952	large slip (preceded by 400 mm rain in November and December)	150
14	Dec 1965	serious slip, 0.7 m displacement	320
15	Feb 1966	renewed movement, 0.3 m displacement (preceded by 385 mm rain in December and January)	190
16	Feb 1977	large slip; 0.4 m subsidence (average)	230

(Table 6.1) Factors of Safety (F) for the Hallaig landslip. After Russell (1985).

Slope height (m)	Slope angle (degrees)	F
300	80	0.75
300	70	0.90
300	60	1.06
350	80	0.69
350	70	0.84
350	60	0.97
350	50	1.12

(Table 7.1) Folkestone Warren: summary of the average values of ø_r' (°), σ_n' and s in the Gault Clay at failure in the 1940, 1937 and 1915 landslips. The original pre-metric data have been used. After Hutchinson (1969).

Landslip	ø(°)		σ_n' (pounds per square foot)		s (pounds per square foot)
	Max u	Min u	Max u	Min u	Max u	Min u
1940	15.1	14.0	4510	4950	1215	1235
1937	16.3	14.0	8340	9740	2440	2430
1915	16.6	13.9	13 170	15 620	3925	3865
σ_n' average effective normal stress on slip-surface in Gault Clay determined graphically using computed values of internal forces u porewater pressure acting on slip-surface s average shear-strength, σ_n'tanø_r', along slip-surface in Gault Clay

(Table 7.2) Results of stability analyses. After Hutchinson (1969).

	Cross section	Pore pressure assumption on slip surface	*Value of ca_r' Gault Clay required for F =* 1.0**		Remarks
			Janbu (⁽⁾)	Morgenstern and Price (°)
1915 landslip	W4 lower profile	Maximum	10.2		Slip surface entirely in Gault Clay
		Minimum	8.3
	W4 upper profile	Maximum	10.3		Slip surface entirely in Gault Clay
		Minimum	8.5
	W4 average profile	Maximum	10.25	9.7	Slip surface entirely in Gault Clay
		Minimum	8.4	7.7
	W6	Maximum	16.55	16.3	ø_r' for small length of slip surface in Chalk Marl at rear of slip = 20°
		Minimum	14.3	13.8
	W8	Maximum	23.85	22.2	ø_r' for small length of slip surface in Lower Chalk at rear of slip = 23°
		Minimum	20.1	18.7
	Weighted average of sections W4 (average), W6 and W8	Maximum	17.6	16.6
		Minimum	14.8	13.9
1937 landslip	W1	Maximum	17.4		ø_r' for small length of slip surface in Lower Chalk at rear of slip = 23°
		Minimum	14.9
	W2	Maximum	18.3	16.2	ø_r' for small length of slip surface in Lower Chalk at rear of slip = 23°
		Minimum	15.9	14.0
1940 landslip	W5	Maximum	13.9	12.5	ø_r' for small length of slip surface in Chalk Marl at rear of slip = 20°
		Minimum	13.0	11.6
	W7	Maximum	19.2	17.6	ø_r' for small length of slip surface in Chalk Marl at rear of slip = 20°
		Minimum	17.6	16.4
	Average of (W5 + W7)/2	Maximum	16.55	15.05	ø_r' for small length of slip surface in Chalk Marl at rear of slip = 20°
		Minimum	15.3	14.0

(Table 9.1) Geological succession in the cliffs of north Norfolk. After Banham (1968).

Chalky outwash sands and gravels		7.5 m
Chalky boulder clay		3.0 m
Brick Kiln Dale Gravels		12.5 m
Gimingham Sands	'Contorted Drift'	3.0 m
Third Till		12.0 m
Mundesley Sands		4.5 m
Second Till	'Cromer Till'	3.0 m
Intermediate Beds	'Cromer Till'	3.0 m
First Till

References