Hi everyone these are the notes I scribbled down as we walked around the quarry and finally put them into some sort of order.
On Saturday the 18th of May 2013 the Stamford and District Geological Society of which I’m a member and The Open University Geological Society went on an organised field trip to Ketton Quarry in Lincolnshire, UK.
The guys who led the trip are Bill Learoyd (Stamford and Dist.Geol Soc) Ken Nye (Stamford and District. Geol Soc) and Donald Cameron (Open University Geol Soc) there guidance and experts was very much appreciated.
Now… this is working quarry so hard hats, and reflective jackets and stout foot wear are essential. Faces are unstable due to blasting and there are muddy arrears and also deep-water to contend with. We were informed that we enter at our own risk but are covered against third party claims!
After a brief talk on Health and Safety we were instructed to only go where directed by a leader or a member of quarry staff which went to plan for the first few hours after that they pretty much gave us free reign.
Ketton Quarry has probably the best section of Middle Jurassic strata in the East Midlands. Our trip through the quarry the quarry revealed rocks from the upper Lias Clay to the Kellaways sands and clays. In the northern part of the pit faulting has been exposed. Fossils where regularly found especially in Blisworth, Cornbrash and Kellaways.
We first looked at the Lias Clay that is only exposed in a flooded test pit and spoil from it was poorly endowed with fossils.
We then walked across a surface of Northampton Sands Ironstone, iron rich calcareous sandstone. This was once made in the local area to supply ore to Corby Steel works, but became uneconomical for extraction some is now used in cement making.
Sitting on the ironstone is the Grantham Formation, made up of silts and sands with rootlets.
The next bed is the base of the Lower Lincolnshire limestone, the bottom of which is Collyweston Slate. Not a true slate but a thin bedded limestone it is still mined locally. Blocks are kept wet and exposed to frost which causes them to split. The thin “slates “are the dressed and used for roofing.
The next stop allowed us to look at the Upper Lincolnshire Limestone. At Ketton this is Oolitic and a near perfect example of this type. This is the limestone used in the cement making at Ketton it is also Freestone, meaning it can be cut in anyway. This is used in many buildings including some of the colleges of Cambridge.
On top of the Lincolnshire Limestone is a series of silts, mostly non-marine, showing various coloured beds containing rootlets this is the other ingredient for cement making. Although unfossiliferous there is evidence of “Dinoturbation “, this is when a dinosaur track way has been heavily used by many dinosaurs (Cestiosaurus in general). Cestiosaurus ( Sauropod ) would have been common in this area during the Middle Jurassic, it would have been the largest dinosaur in these parts and would have been hunted by Megalosaurus ( Allosaurid ). A skeleton of Cestiosaurus was found near Ketton Quarry and its skeleton resides in Leicester Museum.
The higher beds higher beds are not used in cement making and are dumped on site, this is the reason we are gathered here today for most of these beds contain fossils. We looked through a bed of Blisworth Limestone, fine-grained, not Oolitic, overlain by Blisworth Clay. Next up was some Cornbash, a dark coloured massive limestone this was supposed to be the most likely place to find the ammonite Macrocephalites. But it wasn’t to be no one found any from either party.
We finally looked at the Kellaways itself at the end of the day it is the highest Middle Jurassic formation in Ketton Quarry with a bed of Lopha Visible. The Kellaways is overlain itself by chalky boulder clay with occasional derived fossils.
This is the terrain we had to tackle.