Northampton Sand Formation

{{Short description|Geological formation in England}} {{Use dmy dates|date=April 2022}} {{Infobox rockunit | name = Northampton Sand Formation | image = Sundew dragline.jpg | caption = Dragline opencast mining of the ironstone at Weldon, Northamptonshire. | type = Geological formation | age = Aalenian {{Geological range|174|170}} | period = Aalenian | region = East Midlands | country = England | prilithology = Sandstone | otherlithology = Ironstone, Oolitic Limestone | namedfor = Northampton | coordinates = | unitof = Inferior Oolite Group | subunits = Corby Ironstone Member, Duston Member (formerly Variable Beds)<ref name=sutherland>{{cite book|last= Sutherland|first=D.S.| year=2003| title=Northamptonshire Stone| publisher=Dovecote Press| page=31| isbn=190434917X}}</ref> | underlies = Grantham Formation, Rutland Formation, Horsehay Sand Formation | overlies = Whitby Mudstone Formation | thickness = Up to 21 m, typically 4-8 m | extent = Northamptonshire, Lincolnshire | area = | map = | map_caption = | namedby = Sharp | year_ts = 1870 | location_ts = Duston Top Pit | thickness_ts = 11.6 m }}

The '''Northampton Sand Formation''', sometimes called the '''Northamptonshire Sand''', is a geological formation in England dating to the Aalenian stage of the early Middle Jurassic which is placed within the Inferior Oolite Group.<ref>British Geological Survey 2002 ''Kettering'' England and Wales sheet 171, solid & drift geology. 1:50,000 (Keyworth, Nottingham: BGS)</ref><ref name=BGS_Lexicon>{{cite web |url= https://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=NS|title=Northampton Sand Formation |last= |first= |date= |website=BGS Lexicon of Named Rock Units |publisher= British Geological Survey|access-date= 30 July 2018|quote=}}</ref> It was formerly worked extensively in Northamptonshire for its ironstone.

The Northampton Sand Formation constitutes the lowest formation of Inferior Oolite Group in the Midlands and lies upon Whitby Mudstone Formation, the uppermost unit of the underlying Lias Group.<ref name="BGS_Lexicon" /> It attains a maximum thickness of up to {{convert|21|m|ft}} to the north and west of Northampton where it lies in a subterranean basin. In the south, it fades out around Towcester. Northward from the edge of the basin in the upper Lias, under Northampton, it underlies the Bajocian aged Lincolnshire Limestone Formation. A little to the north of Corby Glen ({{gbmapping|TF0027}}) it is at about {{convert|50|m|ft|-1}} from the surface. It fades out under north Lincolnshire as the strata rise towards the Market Weighton Axis.

The formation predominantly consists of sandy ironstone, which when freshly exposed is greenish-grey in colour, which weathers to limonitic brown sandstone.<ref name="BGS_Lexicon" /> It formed in an extensive, shallow sea on the northwestern margin of the London-Brabant Massif.

Fossils found in the formation include remains of an indeterminate sauropod dinosaur (previously attributed to ''Cetiosaurus'' and Brachiosauridae) known from fragments of the bones of the hip (pubis and possibly ischium) collected from near Harlestone in Northamptonshire and acquired by the Natural History Museum in London in 1916 (where it is held under the collection number PV R 9472),<ref>{{Cite journal |last=Naish |first=Darren |last2=Martill |first2=David M. |date=May 2007 |title=Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia |url=https://doi.org/10.1144/0016-76492006-032 |journal=Journal of the Geological Society |volume=164 |issue=3 |pages=493–510 |doi=10.1144/0016-76492006-032 |issn=0016-7649 |quote=Elsewhere, only scrappy remains have been reported, among them a sauropod from the Aalenian Northampton Sands Formation of Northamptonshire|url-access=subscription }}</ref><ref>{{Cite journal |last=Mannion |first=Philip D. |last2=Upchurch |first2=Paul |last3=Barnes |first3=Rosie N. |last4=Mateus |first4=Octávio |date=May 2013 |title=Osteology of the Late Jurassic Portuguese sauropod dinosaur Lusotitan atalaiensis (Macronaria) and the evolutionary history of basal titanosauriforms: Lusotitan and Titanosauriform Evolution |url=https://academic.oup.com/zoolinnean/article-lookup/doi/10.1111/zoj.12029 |journal=Zoological Journal of the Linnean Society |language=en |volume=168 |issue=1 |pages=98–206 |doi=10.1111/zoj.12029 |quote="Fragmentary pelvic material (NHMUK R9472: P. D. Mannion & P. Upchurch, pers. observ., 2012) used for histological work (Reid, 1981) from the Aalenian of the UK (Naish & Martill, 2007) has been suggested to represent an indeterminate brachiosaurid (Hunt et al., 1994; Weishampel et al., 2004). If correctly identified, this would not only represent the earliest known brachiosaurid and titanosauriform, but also the earliest known neosauropod (Naish & Martill, 2007). However, the material is highly incomplete and fragmentary (Reid, 1981), and an identification beyond Sauropoda indet. is not possible."|url-access=subscription }}</ref><ref name="dinosaurdistribution2">Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press {{ISBN|0-520-24209-2}}. pp. 517-607.</ref><ref>{{Cite web |title=Collection specimens - Specimens - PV R 9472 - Data Portal |url=https://data.nhm.ac.uk/object/7b7f0176-d01b-4654-86a9-20aff5150760 |access-date=2025-09-22 |website=data.nhm.ac.uk |language=en-GB}}</ref><ref>{{Cite web |date=2025 |title=Harlestone: Aalenian, United Kingdom |url=https://paleobiodb.org/classic/displayCollResults?collection_no=col:142153 |website=Paleobiology Database}}</ref> and which were subject to a thin sectioning histology study published in ''Nature'' in 1981.<ref>{{Cite journal |last=Reid |first=R. E. H. |date=July 1981 |title=Lamellar-zonal bone with zones and annuli in the pelvis of a sauropod dinosaur |url=https://www.nature.com/articles/292049a0 |journal=Nature |language=en |volume=292 |issue=5818 |pages=49–51 |doi=10.1038/292049a0 |issn=0028-0836|url-access=subscription }}</ref> A species of horseshoe crab, ''Mesolimulus woodwardi'' has been described based on a fossil found in the Northampton Sand in the vicinity of Great Doddington near Wellingborough.<ref>{{Cite journal |last1=Bicknell |first1=Russell D. C. |last2=Błażejowski |first2=Błażej |last3=Wings |first3=Oliver |last4=Hitij |first4=Tomaž |last5=Botton |first5=Mark L. |date=August 2021 |editor-last=Zhang |editor-first=Xi‐Guang |title=Critical re‐evaluation of Limulidae uncovers limited Limulus diversity |url=https://onlinelibrary.wiley.com/doi/10.1002/spp2.1352 |journal=Papers in Palaeontology |language=en |volume=7 |issue=3 |pages=1525–1556 |doi=10.1002/spp2.1352 |s2cid=233783546 |issn=2056-2799|url-access=subscription }}</ref><ref>{{Cite web |date=2020 |title=Doddington, near Wellingborough (Jurassic to of the United Kingdom) |url=https://paleobiodb.org/classic/basicCollectionSearch?collection_no=216791&is_real_user=1 |website=Paleobiology Database}}</ref>

The formation is a significant emitter of radon gas, with a layer of relatively uranium rich (~ 20 ppm on average) phosphatic pebbles located in a 30 cm thick layer at the base of the formation being a particularly strong emitter, though significant levels of radon emanate from the whole of the formation.<ref>{{Cite journal |last=Scheib |first=C. |last2=Appleton |first2=J.D. |last3=Miles |first3=J.C.H. |last4=Hodgkinson |first4=E. |date=December 2013 |title=Geological controls on radon potential in England |url=https://linkinghub.elsevier.com/retrieve/pii/S0016787813000291 |journal=Proceedings of the Geologists' Association |language=en |volume=124 |issue=6 |pages=910–928 |doi=10.1016/j.pgeola.2013.03.004|url-access=subscription }}</ref>

==Commercial exploitation== There is a description of the twentieth century exploitation of the Northampton Sand for iron-smelting in the Wellingborough article.

==References== {{Reflist}}

==Bibliography== *Kent, P. & Gaunt, G.D. ''British Regional Geology Eastern England to The Wash'' (1980) {{ISBN|0-11-884121-1}} *Hains, B.A. & Horton, A. ''British Regional Geology Central England'' (1969) {{ISBN|0-11-880088-4}} *British Geological Survey ''1:50 000 Series. Stamford. Sheet 157'' Solid & Drift Edition (1978)

{{coord|52.8313|N|0.5171|W|type:landmark_region:GB|display=title}}

Category:Aalenian Stage Category:Jurassic System of Europe