OR/14/008 Obsolete lithostratigraphic terms and codes

Aldiss, D T. 2014. The stratigraphical framework for the Palaeogene successions of the London Basin, UK. Nottingham, UK, British geological Survey. (OR/14/008)

This list is in alphabetical order of Lexicon Codes (see Section 1.5). It is mainly restricted to unit names used on BGS maps and in other BGS publications, with entries in the BGS Lexicon.

Extant' 'Lexicon' 'code	Obsolete' 'Lexicon' 'code	Obsolete name	Current' 'name' 'for equivalent or part-equivalent
	BBD	Reading Bottom Bed	Upnor Formation
	BGB	Bagshot Beds	Part of Bracklesham Group
	BGBL	Lower Bagshot Beds	Near-equivalent to Bagshot Formation
	BGBM	Middle Bagshot Beds	Near-equivalent to Windlesham Formation
	BGBR	Bagshot Beds and Bracklesham Beds (undifferentiated)	Part of Bracklesham Group
	BGBU	Upper Bagshot Beds	Camberley Sand Formation
BLB		Blackheath Beds	Blackheath Member
	HAC	Hales Clay Member	Orwell Member (Harwich Formation) and Upnor Formation
	LCBA	London Clay Basement Bed	Equivalent or part equivalent to Walton Member or Harwich Formation
	LLTE	Lower London Tertiaries	Harwich Formation, Lambeth Group and Thanet Formation, undifferentiated
	MCL	Mottled Clay (Reading Formation)	Reading Formation
OH		Oldhaven Beds	Oldhaven Member
	RFBB	Reading Formation Basement Bed	Upnor Formation
TAB		Thanet Sand Formation	Thanet Formation
	TS	Thanet Sand	Thanet Formation
	WLOH	Woolwich Beds – Oldhaven Beds	Woolwich Formation and Harwich Formation undifferentiated
	WRB	Woolwich and Reading Beds Formation	Woolwich Formation and Reading Formation undifferentiated
		Blackwall Rock	not known

Figure 1 Selected structures controlling the London Basin. This map shows the areas of the traditional English counties, prior to the formation of the modern Boroughs, Districts and Unitary Authorities, although it includes the area of the Greater London Authority

From Ogg et al. (2008), and from King (2006) after Berggren et al. (1995). Age/Stage names for the Neogene and Quaternary have been omitted for simplicity.

Table 1 Chronostratigraphical subdivisions of the Cenozoic Era

PERIOD	EPOCH		AGE/STAGE	Age of base (Ma)
QUATERNARY	Holocene Pleistocene			2.59
NEOGENE	Pliocene			5.33
	Miocene			23.03
PALAEOGENE	Late	Oligocene	Chattian	28.4
	Early		Rupelian	33.9
	Late	Eocene	Priabonian	37.2
	Mid		Bartonian	40.4
			Lutetian	48.6
	Early		Ypresian	55.8
	Late	Paleocene	Thanetian	58.7
			Selandian	61.1
	Early		Danian	65.5

Table 2 Stratigraphical hierarchy in the Palaeogene of the London Basin.

Group	Formation	Member	Bed
Bracklesham	Camberley Sand
	Windlesham		Stanners Hill Pebble
	Bagshot	Swinley Clay	St Ann’s Hill Pebble
Thames	London Clay	Claygate Sheppey Aveley Ockendon Walton
	Harwich	Swanscombe Oldhaven Blackheath Wrabness Orwell	Lessness Shell Harwich Stone Band Suffolk Pebble
Lambeth	Woolwich	Woolwich' Sands Upper Shelly Clay Striped Loams Laminated Beds Lower Shelly Clay Shorne	Cobham Lignite
	Reading	Upper' Mottled Clay Lower Mottled Clay
	Upnor
Montrose	Thanet	Reculver Sand Pegwell Silt Kentish Sands Stourmouth Silt Base Bed
			Cliffs End Greensand Bullhead
	Lista	Ormesby Clay

Note that in normal usage, unit names are terminated by the rank term at the head of the column, other than those shown in italic script, which are informal.

Table 3 Subdivision of the Upper Palaeogene strata of the London Basin

Warburton 1822	Prestwich 1847	Dewey and Bromehead 1915	King 1981	Bristow 1982	Curry 1992	Current BGS Framework
						London Basin		Hampshire Basin
Younger beds have been removed by erosion								Barton Formation	Bracklesham Group
								Selsey Sand Formation
Bagshot Sand	Upper Bagshot Sands	Barton Beds			Bagshot Formation	Camberley Sand Formation	Bracklesham Group
	Middle Bagshot Sands	Bracklesham Beds	Middle Bagshot Beds Middle unit Lower unit			Windlesham Formation
								Marsh Farm Formation
								Earnley Sand Formation
						Swinley Clay Member Bagshot Formation		Wittering Formation
	Lower Bagshot Sands	Bagshot Beds	Virginia Water Formation	Bagshot Beds
London Clay Formation

Taken from a draft document prepared by R A Ellison and I T Williamson, BGS, in 1998.