GLA 29: The Gravel Pits, Northwood

GLA 29: The Gravel Pits, Northwood
Proposed RIGS
London Borough of Hillingdon, TQ 083 913
Ownership: Local Authority. Open access.

The Northwood Gravel pits, along with other pits in the area, were a major source of gravel for mending local roads up to the end of the 19th century. The pits were excavated in the Palaeogene Reading Formation of the Lambeth Group. These comprise sands, silts, clays and gravels deposited by rivers on a coastal plain under sub-tropical conditions. The Reading Formation forms the surface in the low-lying parts of Pinner, Northwood, Ruislip and Ickenham. Local variations are the large proportion of sand in the strata and the replacement of the usual Bottom Bed by a seam of pebbles 1.25-1.80m thick*. This ‘Bottom Bed’ is the Upnor Formation upon which the Reading Formation rests.

The gravel pits were not enclosed under the Enclosures Act in the early 19th century so they were allowed to continue as a source of gravel. However, the gravel was described as ‘worked out’ in 1898 and the area was saved as a public amenity in commemoration of Queen Victoria’s diamond jubilee the previous year. In 1905, it was formally conveyed to the Ruislip & Northwood Urban District Council and later transferred to the London Borough of Hillingdon. Now covered largely by woodland, the area is managed by the council, with the help of the “Friends of Northwood Gravel Pits” established by the Northwood Residents’ Association during the conservation work to open up the area, make good pathways through the woods and establish a nature trail. The site is overgrown with few exposures in the hillocks within the site and in the steep face at the edge of the pits adjoining the nearby housing estate. However, the Reading Beds sands can be well seen in the debris excavated largely by animals.


* Woodward H B & Chatwin C P (revised by Bromehead C E N), 1922: The Geology of London District. Memoir of the Geological Survey, p 22 (this memoir can be downloaded from

Animal excavations in hillock exposing the Reading Beds sands
Source: Dave Brook

gla29 animl burrows

Reading Beds sand debris excavated by animals in perimeter face of pitsSource: Dave Brook

gla29 sand debris

Site Map OS Topography © Crown Copyright
Source: London’s foundations, page 163

gla29 map


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