302:
125:
491:, at the base of the Lower Greensand is an escarpment, where the Hythe Beds overlie the Atherfield and Weald Clays, which is particularly susceptible to landslide. Most slip is attributed to massive sandstones overlying weaker shales and clays. The back part of the slip in strongly permeable locations is prone to be straight downward on a rotational slip plane. This shift leaves a steep back face, or back-scar, with a toe raised significantly less.
288:
480:
movements of a mass of earth or rock sliding along a steep slope. They tend to occur after sustained heavy rain, when the water saturates overlying rock, making it heavy and liable to slide, others occur via soil creep is a very slow movement, occurring on very gentle slopes because of the way soils repeatedly expand and contract in wet and dry periods. When the soil dries out, it contracts vertically, assisting the soil slowly down a slope.
270:
479:
The Lower
Greensand is one of the most landslide-susceptible formations in the UK with at least 288 known occurrences in South-East England recorded to the year 2000. Of the formations within the Lower Greensand, the Atherfield Clay is the most prone to landslip. Landslides are occasional, rapid
341:
The Lower
Greensand typically comprises loose, unconsolidated sandstone (termed rubblestone/rubble in construction) and sands of varying grain size with subordinate amounts of siltstones, mudstones (containing
369:. These clays are overlain by green sandy clays and silts and finally homogeneous fine grained sands. The sediments are noted to become increasingly fine grained and glauconitic to the east.
699:
392:. The Group is the lowermost of two geological units that take their name from their colouration due to the presence of the mineral glauconite, the other being the
704:
468:
506:. Later translational slides have developed along a shear zone at the boundary between the slip material and the undisturbed underlying
396:. The unit was deposited in shallow marine conditions. In southern England the unit sharply but continuously overlies rocks of the
166:
605:
423:, the Lower Greensand can usually be subdivided to formational levels with varying properties into, in ascending order, the
305:
The Lower
Greensand as a broad zone between the brick-patterned chalk (a type of limestone) and the interior large c-shape
623:
Modelling the impact of predicted climate change on landslide frequency and magnitude in SE England. Engineering
Geology
301:
467:. In North Wiltshire as the Calne Sands Formation and in parts of Wiltshire, Oxfordshire and Buckinghamshire as the
333:. It predominantly consists of sandstone and unconsolidated sand that were deposited in shallow marine conditions.
124:
424:
393:
172:
154:
566:
522:
faces inland, exerting a steady force, where the water is subterranean, outward towards the coastal cliffs.
536:
456:
182:
714:
709:
592:
Geology of the country around
Hastings and Dungeness: Memoir for 1:50,000 geological sheets 320 and 321
436:
401:
389:
176:
141:
162:
531:
158:
365:
the lowermost part of the group is recognised by green glauconitic clays with a basal bed of
488:
405:
378:
366:
318:
652:
546:
541:
499:
452:
641:
Analysis of the distribution and characteristics of landslips in the Weald of East Sussex
519:
464:
444:
293:
199:
186:
693:
556:
484:
397:
210:
83:
38:
448:
413:
350:. The name "greensand" is derived from the presence of the green coloured mineral
571:
511:
460:
420:
362:
58:
17:
515:
507:
503:
351:
330:
306:
103:
68:
551:
510:. This sort of rotational slip occurs regularly along the coastline between
347:
248:
238:
108:
52:
609:. Research Report RR/08/03. British Geological Survey, Keyworth. Page 15
409:
343:
214:
98:
93:
78:
73:
63:
275:
130:
113:
88:
377:
The Lower
Greensand Group was deposited during the latter part of the
561:
440:
386:
382:
326:
322:
46:
42:
358:
684:
495:
252:
606:
A stratigraphical framework for the Lower
Cretaceous of England
655:
502:(and all material above) have compromised sandstone blocks of
621:
Collison , A., Wade, S., Griffiths, J. & DEHN, M. (2000)
603:
Hopson, P.M., Wilkinson, I.P. and Woods, M.A. (2010)
483:
A common geomorphological, chiefly dependent on the
317:is a geological unit present across large areas of
281:
263:
258:
244:
234:
229:
221:
205:
195:
147:
137:
32:
498:, where a rotational slump occurred, slips of the
189:, Seend Ironstone Formation, Calne Sands Formation
669:British Regional Geology: The Wealden District.
309:. Many towns shown are on the Lower Greensand.
8:
590:Lake, R.D. & Shepard-Thorn, E.R. (1987)
354:, which forms in shallow marine conditions.
643:. MSc dissertation, University of Brighton.
617:
615:
123:
29:
667:Gallois, R.W. & Edmunds, M.A. (1965)
671:Her Majesty’s Stationery Office, London.
300:
700:Geological groups of the United Kingdom
583:
175:, Hythe Formation, Sandgate Formation,
635:
633:
631:
7:
594:. British Geological Survey, London.
25:
705:Lower Cretaceous Series of Europe
685:British Geological Survey lexicon
455:– it is referred to as the
286:
268:
404:it covered previously emergent
321:. It was deposited during the
167:Monk's Bay Sandstone Formation
1:
225:~250 m in South Western Weald
129:Lower Greensand outcrop near
653:Basic Summary of Landslides
731:
425:Atherfield Clay Formation
400:. While elsewhere as the
394:Upper Greensand Formation
173:Atherfield Clay Formation
155:Atherfield Clay Formation
122:
37:
567:Wadhurst Clay Formation
537:Geology of East Sussex
457:Woburn Sands Formation
310:
183:Woburn Sands Formation
315:Lower Greensand Group
304:
209:In Southern England,
33:Lower Greensand Group
439:. North and west of
437:Folkestone Formation
329:stages of the Early
177:Folkestone Formation
572:West Sussex#Geology
494:At ‘The Roughs’ in
475:Engineering geology
463:it is known as the
381:Period, during the
142:Stratigraphic group
39:Stratigraphic range
658:Bitesize Geography
639:Codd, J.W. (2007)
443:– including
433:Sandgate Formation
311:
163:Sandrock Formation
532:Ashdown Formation
416:overlying them.
367:phosphate nodules
346:and similar) and
299:
298:
159:Ferruginous Sands
16:(Redirected from
722:
672:
665:
659:
650:
644:
637:
626:
619:
610:
601:
595:
588:
489:hydraulic action
379:Early Cretaceous
319:Southern England
292:
290:
289:
274:
272:
271:
127:
118:
55:
30:
21:
730:
729:
725:
724:
723:
721:
720:
719:
690:
689:
681:
676:
675:
666:
662:
651:
647:
638:
629:
620:
613:
602:
598:
589:
585:
580:
547:Greensand Ridge
542:Geology of Kent
528:
500:Atherfield Clay
485:local hydrology
477:
469:Seend Ironstone
453:Buckinghamshire
429:Hythe Formation
375:
339:
287:
285:
269:
267:
133:
117:
116:
111:
106:
101:
96:
91:
86:
81:
76:
71:
66:
61:
50:
49:
28:
27:Geological unit
23:
22:
18:Hythe Formation
15:
12:
11:
5:
728:
726:
718:
717:
712:
707:
702:
692:
691:
688:
687:
680:
679:External links
677:
674:
673:
660:
645:
627:
625:, 55, 205-218.
611:
596:
582:
581:
579:
576:
575:
574:
569:
564:
562:Surrey#Geology
559:
554:
549:
544:
539:
534:
527:
524:
520:drainage basin
476:
473:
465:Faringdon Sand
445:Cambridgeshire
402:sea level rose
374:
371:
338:
335:
297:
296:
283:
279:
278:
265:
261:
260:
256:
255:
246:
242:
241:
236:
232:
231:
227:
226:
223:
219:
218:
207:
203:
202:
200:Selborne Group
197:
193:
192:
191:
190:
187:Faringdon Sand
179:
169:
153:Wessex Basin:
149:
145:
144:
139:
135:
134:
128:
120:
119:
112:
107:
102:
97:
92:
87:
82:
77:
72:
67:
62:
57:
56:
35:
34:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
727:
716:
713:
711:
708:
706:
703:
701:
698:
697:
695:
686:
683:
682:
678:
670:
664:
661:
657:
654:
649:
646:
642:
636:
634:
632:
628:
624:
618:
616:
612:
608:
607:
600:
597:
593:
587:
584:
577:
573:
570:
568:
565:
563:
560:
558:
557:Hastings Beds
555:
553:
550:
548:
545:
543:
540:
538:
535:
533:
530:
529:
525:
523:
521:
517:
513:
509:
505:
501:
497:
492:
490:
486:
481:
474:
472:
470:
466:
462:
458:
454:
450:
446:
442:
438:
434:
430:
426:
422:
417:
415:
414:unconformably
411:
407:
403:
399:
398:Wealden Group
395:
391:
388:
384:
380:
372:
370:
368:
364:
360:
355:
353:
349:
345:
336:
334:
332:
328:
324:
320:
316:
308:
303:
295:
284:
280:
277:
266:
262:
257:
254:
250:
247:
243:
240:
237:
233:
228:
224:
220:
216:
212:
211:Wealden Group
208:
204:
201:
198:
194:
188:
184:
180:
178:
174:
171:Weald Basin:
170:
168:
164:
160:
156:
152:
151:
150:
146:
143:
140:
136:
132:
126:
121:
115:
110:
105:
100:
95:
90:
85:
80:
75:
70:
65:
60:
54:
51:125–110
48:
44:
40:
36:
31:
19:
715:Aptian Stage
710:Albian Stage
668:
663:
648:
640:
622:
604:
599:
591:
586:
518:, where the
493:
482:
478:
449:Bedfordshire
432:
428:
418:
376:
373:Stratigraphy
356:
340:
314:
312:
213:, elsewhere
471:Formation.
461:Oxfordshire
421:Weald Basin
363:East Sussex
694:Categories
578:References
516:Folkestone
508:Weald Clay
504:Hythe Beds
435:, and the
352:glauconite
348:limestones
331:Cretaceous
307:Weald Clay
181:Marginal:
552:Greensand
385:to Early
344:smectites
337:Lithology
249:Siltstone
239:Sandstone
230:Lithology
222:Thickness
196:Underlies
148:Sub-units
526:See also
487:such as
410:Jurassic
259:Location
215:Jurassic
206:Overlies
45:– Early
419:In the
412:rocks,
357:In the
282:Country
276:England
235:Primary
131:Dryhill
441:London
431:, the
427:, the
390:stages
387:Albian
383:Aptian
327:Albian
323:Aptian
291:
273:
264:Region
47:Albian
43:Aptian
512:Hythe
459:. In
406:highs
359:Weald
245:Other
217:rocks
514:and
496:Kent
451:and
325:and
313:The
253:Clay
138:Type
59:PreꞒ
656:BBC
408:of
361:of
696::
630:^
614:^
447:,
294:UK
251:,
185:,
165:,
161:,
157:,
109:Pg
53:Ma
41::
114:N
104:K
99:J
94:T
89:P
84:C
79:D
74:S
69:O
64:Ꞓ
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
