{{Unreferenced, date=December 2009
The Lower Estuarine Series, also called in more modern publications, the Grantham Formation, is a relatively complex but generally thin set of
geological
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other E ...
strata which are usually considered as a group. It forms a lower part of the (
Bajocian
In the geologic timescale, the Bajocian is an age and stage in the Middle Jurassic. It lasted from approximately 170.3 Ma to around 168.3 Ma (million years ago). The Bajocian Age succeeds the Aalenian Age and precedes the Bathonian Age.
Stra ...
)
Inferior Oolite Group
The Inferior Oolite is a sequence of Jurassic age sedimentary rocks in Europe. It was deposited during the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Pet ...
, which lies in the Middle
Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
. Where found, it is normally above the
Northampton sand
The Northampton Sand Formation, sometimes called the Northamptonshire Sand, is a Middle Jurassic geological formation which is placed within the Inferior Oolite Group. It was formerly worked extensively in Northamptonshire for its ironstone.
T ...
and below the
Lower Lincolnshire Limestone Member.
The group is found in the
East Midlands of
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
and was formed when the
London-Brabant Island
The London-Brabant Massif or London-Brabant Platform is, in the tectonic structure of Europe, a structural high or massif that stretches from the Rhineland in western Germany across northern Belgium (in the province of Brabant) and the North Sea t ...
was
drifting through the low northern
latitude
In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...
s, in conditions represented today by the
Sahara Desert
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, photo_caption = The Sahara taken by Apollo 17 astronauts, 1972
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. The land was eroded by wind action and by occasional downpours which carried the debris to the margin of a shallow sea.
It is not a major feature and does not generally extend to much more than 0.5 metre thick. It does, however, occasionally achieve 7.5 metres of thickness.
Geology of England
Geologic formations of the United Kingdom