78:
626:
c60 metres altitude, Bush Hill lies to the south at c50 metres, and the two watercourses on either side are at about 30 metres. This topographical configuration invites speculation that the col is also a wind gap, in this case marking a former line of
Salmons Brook, when it may once have flowed eastwards to the Lea across this "wind gap" and then along today's line of Saddlers Mill Stream. The brook would later have been diverted to its present course by stream capture. However, in this case the col could equally have come about through other causes, such as
319:(Bush Hill itself is today an example of inverted relief, albeit on a small scale. Inversion of relief occurs "when materials on valley floors are, or become, more resistant to erosion than the adjacent valley slopes. As erosion proceeds, the valley floor becomes a ridge bounded by newly formed valleys on each side". In the case of Bush Hill, the permeable Boyn Hill Gravel on the hill protected the otherwise easily eroded London Clay underneath from being removed, while nearby watercourses cut down into exposed London Clay).
267:
34:
367:
350:
climatic conditions". And, at such times, soil cover and vegetation would have been much thinner than today, thus facilitating greater erosion. Furthermore, as the River Lea itself cut down as it moved eastwards, it lowered the base level of its tributary stream, Salmons Brook. That would have enabled the brook to become further incised into the higher ground to the west of the Lea flood plain.
346:, has a notably steep eastern slope. Associated with that is the fact that all the tributaries of that section of Salmons Brook are on its west side. So it is possible that that section of the brook has, like the lower River Lea, also shifted eastwards somewhat since the Anglian glaciation (and, if so, presumably for the same reason).
675:
625:
Elsewhere, the railway line between
Enfield Chase and Grange Park stations crosses from the east side of the watershed between Salmons Brook and Saddlers Mill Stream to the west side at a col at an altitude of about 40 metres, just behind Old Park Grove. Windmill Hill lies to the north of this col at
581:
It is not uncommon to find similar instances of inverted relief in the London area, with London Clay hills capped by valley gravel. Other examples are: Forty Hill (also capped by Boyn Hill Gravel, laid down by the River Lea), about 4 kilometres to the north-east of Bush Hill; and, in the catchment of
315:
In the case of
Salmons Brook immediately after the glaciation, that stream joined the River Lea somewhere around Bush Hill, where there is a deposit of "Boyn Hill Gravel". That gravel, which is on the highest of the river terraces left by the post-Anglian lower River Lea, marks the line followed by
357:
at the junction of Waggon Road and the A111, where the east-flowing Monken Mead Brook turns sharply to the south to become the upper part of Pymmes Brook, indicates that Monken Mead Brook once continued eastwards as a tributary of
Salmons Brook. It has been captured by Pymmes Brook in the recent
349:
In addition, that section of the
Salmons Brook valley today seems disproportionately deep for such a small stream - for example, at Slades Hill. But we are currently in an interglacial period, and the stream would have been flowing more strongly than today at times of "high discharge, under cold
81:
Clarendon Arch is a barrel vaulted tunnel which carries
Salmons Brook below the New River at Bush Hill. Originally the brook was spanned by a bridge constructed between 1608 and 1613. In 1682 the bridge was replaced by an arch named after the then Governor of the New River Company, the Earl of
322:
During the course of the following 400,000 years, the lower Lea moved steadily eastwards, leaving river terrace deposits of decreasing age and altitude as it did so, as well as a relatively steep eastern slope. (This eastward shift has been attributed to an underlying
304:, followed valleys which had been in existence before the ice sheet covered the land, or whether they fashioned a substantially different landscape after the ice retreated. But it is known that today's tributaries of the upper Lea, such as the Rivers
560:. Transactions and Papers (Institute of British Geographers), 1959, No. 26, pp. 37-50. See in particular Figure 1, Figure 4, and page 49 - "There is seen to be a general correspondence between the present and pre-glacial drainage lines".
293:, down towards the newly formed lower River Lea. They, and their own tributaries, cut down successively through till left by the ice sheet, then through "Dollis Hill Gravel", and then into Claygate Beds and London Clay below.
312:, follow broadly the same lines as pre-glaciation valleys, so, by analogy, it is quite possible that elements at least of the pre-glaciation topography of the lower Lea basin are reflected in today's relief.
282:, and that river cut into and followed in part the line of the former proto-Mole-Wey. It flowed into the newly diverted Thames, which at that time was spread over a wide flood plain extending as far north as
652:
289:
And, as the ice sheet retreated, west bank tributaries of the lower Lea, such as
Salmons Brook, flowed eastwards and south-eastwards from higher ground running roughly south–north through
1106:
182:" - has a higher sand content. In some parts of the higher sections of the catchment area, the London Clay is overlain by "Stanmore Gravel" and "Dollis Hill Gravel" (both
82:
Clarendon. This was commemorated by a carved ornamental keystone with an inscription. The arch was again rebuilt in 1725 and is now a statutory listed Grade II structure.
135:
before flowing under
Montagu Road to be joined by the culverted Saddlers Mill Stream in an area prone to serious flooding. Running through wasteland and under the
590:
and Dollis Hill, where Dollis Hill Gravel, laid down in the valley bottom of the long-disappeared north-flowing proto-Mole-Wey river which flowed through the
487:
The North London
British Geological Survey (BGS) map at a scale of 1:50,000, which covers the Salmons Brook catchment area, can be viewed online at
458:. On the Stanmore Gravel, which occurs in the Salmons Brook catchment area only around the Potters Bar M25 interchange, see Bridgland, DR (1994),
194:
deposits on the
Salmons Brook valley floor. And east of Bush Hill, the brook crosses extensive Quaternary river terrace deposits laid down by the
77:
522:
1111:
734:
411:
236:. As a result of the glaciation, the Thames was diverted to a more southerly route, broadly along the line of its current course.
140:
335:. There, it merges today with Pymmes Brook, which in turns flows southwards before joining the River Lea near Tottenham Lock.
120:
327:.) Salmons Brook thus extended its course south-eastwards from Bush Hill, across the valley floor of the lower Lea, through
374:
The brook has a history of flooding. The last major incident was in October, 2000 in the Montagu Road area of Edmonton.
259:, at what is today an altitude of around 60 metres. It was this river which, during the course of the early and middle
201:
As a west bank tributary of the lower River Lea, Salmons Brook came into being about 400,000 years ago, after the
1101:
683:
27:
924:
436:
670:
616:
Bridgland, DR (1994), The Quaternary of the Thames. Chapman & Hall, London, chapter 1, "Terrace Formation"
423:
455:
727:
132:
1116:
975:
944:
639:
630:
on one or both sides. So the stream capture hypothesis currently remains in the realm of speculation only.
478:(British Geological Survey) for more information on the distribution of all the formations mentioned here.
144:
38:
450:
There are outcrops of most of the formations mentioned here in the Cockfosters - Trent Park area. See:
505:
339:
148:
54:
435:
More information about the course of Salmons Brook, with images, can be found in Watson G, 2004-05,
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Middle and Late Pleistocene glacial lakes of lowland Britain and the southern North Sea Basin
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50:
1060:
1050:
1020:
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It is not known at present whether Salmons Brook, and other west bank tributaries such as
239:
Prior to the Anglian glaciation, a "proto-Mole-Wey" river was flowing northwards from the
205:. During that glaciation, ice from the north of England advanced at least as far south as
1075:
1070:
1010:
1000:
898:
823:
776:
627:
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521:. Quaternary International, Volume 260, 18 May 2012, Pages 115-142, Fig. 7A. Online at
332:
328:
274:
When the Anglian ice sheet diverted the Thames southwards, the Mole-Wey was cut off at
33:
676:
Salmons Brook by Churchyard Recreation Ground in Edmonton Green, on Google Street View
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The Sub-Glacial Surface in East Hertfordshire and Its Relation to the Valley Pattern
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The drainage pattern in this area continues to evolve. For example, the pronounced
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160:
504:, Géographie physique et Quaternaire, vol. 51, n° 3, 1997, pp. 337-346. Online at
370:
Saddlers Millstream (right) merges with Salmons Brook below Montagu Road, Edmonton
607:, Proceedings of the Geologists' Association, Volume 34, Issue 3, 1923, page 251.
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954:
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309:
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278:. Meltwater from the retreating Anglian ice sheet gave birth to a south-flowing
260:
244:
179:
175:
92:
67:
547:
Ellison, RA (2004), Geology of London, British Geological Survey, Fig. 29, p54.
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Quaternary River Diversions in the London Basin and the Eastern English Channel
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343:
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The main geological formation underlying the Salmons Brook catchment area is
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Managing flood risk in the lower Lea catchment, today and in the future
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813:
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32:
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Topographic map of the Pymmes Brook catchment area, north London
187:
716:
462:, Chapman & Hall, London, chapter 2, "Harrow Weald Common".
263:, deposited the "Dollis Hill Gravel" at successive altitudes.
651:
On flood prevention strategy, see Environment Agency, 2013,
224:
flowed north-eastwards via Watford, through what is now the
438:
Lower Edmonton- Transport and Watercourses - Salmon's Brook
538:, Geological Magazine, Volume 116, Issue 1, January 1979.
186:
pre-glacial fluvial deposits), and by Quaternary glacial
572:, Pain CF & Ollier CD, Geomorphology 12 (1995) p151.
570:
Inversion of relief - a component of landscape evolution
525:. See also Bridgland, DR and Gibbard, PL (1997), Fig. 3.
123:
to emerge at Plevna Road, where it runs alongside the
452:
Guide to London's Geological sites - GLA55 Trent Park
139:
railway, it is quickly joined by the outflow of the
963:
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801:
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754:
536:Middle Pleistocene drainage in the Thames Valley
517:Murton, Della K. and Murton, Julian B. (2012),
151:, the brook can be seen as it passes under the
178:. The uppermost part of this formation - the "
728:
671:Salmons Brook photos and detailed information
454:, London Geodiversity Partnership, online at
8:
316:the Lea after the retreat of the ice sheet.
255:, to join the proto-Thames somewhere around
127:. It skirts the walled Edmonton Federation
107:and to Bush Hill where it passes under the
1107:Geography of the London Borough of Enfield
735:
721:
713:
190:. From Slades Hill southwards, there are
70:, probably named from the family of John
404:Oxford Dictionary of London Place Names
383:
500:Bridgland, DR and Gibbard, PL (1997),
470:
468:
605:Notes on the Geology of Epping Forest
7:
220:Until the Anglian glaciation, the
14:
66:Salmons Brook is marked thus on
594:, is now found on the hilltops.
141:Deephams Sewage Treatment Works
74:of Edmonton mentioned in 1274.
1:
657:, especially pages 31 and 33.
603:Wells, AK and Wooldridge SW,
508:. See in particular Figure 1.
167:Geology, origin and evolution
99:on the borders of the former
1112:Tributaries of the River Lea
460:The Quaternary of the Thames
441:, retrieved 7 February 2022.
22:is a minor tributary of the
456:londongeopartnership.org.uk
1133:
642:Retrieved 24 November 2007
393:Retrieved 16 December 2008
342:, Salmons Brook, like the
103:, and flows east close to
506:www.erudit.org/fr/revues/
426:Retrieved 15 October 2009
414:Retrieved 26 October 2008
338:From Hadley Road down to
228:, then eastwards towards
91:The brook rises south of
28:London Borough of Enfield
556:Brown, Joyce C. (1959),
133:Tottenham Park Cemetery
976:Broxbourne Mill Stream
489:largeimages.bgs.ac.uk/
391:British history online
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271:
145:Eley Industrial Estate
143:. Flowing through the
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58:
39:Eley Industrial Estate
640:Photographs of floods
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269:
80:
41:before flowing under
37:Salmons Brook at the
36:
534:Gibbard, PL (1979),
424:Saddlers Mill Stream
378:Notes and References
159:before merging with
149:Edmonton Incinerator
68:Rocque's map of 1754
57:is in the background
55:Edmonton Incinerator
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592:Finchley depression
249:Finchley depression
153:North Circular Road
43:North Circular Road
829:Welwyn Garden City
476:BGS Geology Viewer
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203:Anglian glaciation
125:Pymmes Brook Trail
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1089:
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1081:Wormleybury Brook
986:Coppermill Stream
964:Minor tributaries
918:Major tributaries
844:Stanstead Abbotts
358:geological past.
226:Vale of St Albans
147:and close to the
131:Cemetery and the
26:, located in the
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1056:Spital Brook
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1026:Pymmes Brook
1016:Lewsey Brook
940:River Mimram
904:Canning Town
889:Hackney Wick
793:River Thames
762:Bedfordshire
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955:River Stort
935:River Ching
930:River Beane
869:Ponders End
802:Settlements
702: /
584:River Brent
340:Grange Park
291:Potters Bar
261:Pleistocene
245:North Downs
176:London Clay
93:Potters Bar
1096:Categories
1036:Rags Brook
1031:River Quin
854:Broxbourne
687:51°36′32″N
230:Chelmsford
184:Quaternary
157:Angel Road
105:Trent Park
47:Angel Road
950:River Rib
925:River Ash
894:Stratford
879:Tottenham
849:Hoddesdon
819:Harpenden
690:0°02′38″W
523:coek.info
325:monocline
284:Islington
257:Hoddesdon
234:North Sea
215:Chingford
196:River Lea
117:culverted
111:to enter
109:New River
62:Etymology
24:River Lea
909:Leamouth
874:Edmonton
859:Cheshunt
834:Hertford
809:Leagrave
755:Counties
362:Flooding
355:wind gap
276:Richmond
232:and the
211:Finchley
192:alluvium
113:Edmonton
51:Edmonton
748:England
207:Watford
72:Salemon
410:
306:Mimram
251:" and
173:Eocene
129:Jewish
119:under
87:Course
53:. The
814:Luton
786:Mouth
767:Essex
331:, to
310:Stort
241:Weald
95:, in
839:Ware
582:the
474:See
408:ISBN
308:and
300:and
243:and
213:and
188:till
155:at
45:at
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746:,
467:^
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217:.
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163:.
49:,
30:.
736:e
729:t
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491:.
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