In the 19th century fertiliser was at a premium. Soot, bones, ashes, dung, maltings and various other things were tried in order to increase the productivity of soils. The most effective fertiliser was guano, bird droppings from S America (but it was highly prized by other nations and cost money to transport and was very expensive). Suffice to say that guano didn't appear on many farms over here – but something else did. A cheap alternative was discovered, phosphate containing nodules that could be dug out of the ground, here in Blighty, in the Greensand layer (as it strikes through Cambridgeshire and the Isle of Ely).
At http://en.wikipedia.org/wiki/Coprolite … we learn that it is fossilised droppings. The dung itself can contain teeth, bones and claws from consumed animals but basically the coprolite has been through a chemical change and is quite different in structure from droppings that have been buried and preserved intact. The famous geologist, the Reverend William Buckland (1829), came up with the term, a combination of 'dung' and 'stone' (in the Greek). The famous fossil hunter Mary Anning, at Lyme Regis and Charmouth, found coprolites in the abdominal region of ichtyosaur skeletons (in the Lias Formation). She also cracked some of them open and found fishbones and scales. Coprolites have a wide range of dates as well, from the Cambrian to the Recent, but are most famous as dinosaur droppings (from the Jurassic and Cretaceous periods).
At www.shillington-history.org.uk there is a page on the coprolite industry – which gravitated all the way along the Greensand into Bedfordshire and Buckinghamshire – and therefore, Shillington. Here, it says that it was thought coprolites were just dinosaur droppings (the perceived wisdom for a number of years) but they now seem to come from a variety of animals – including sea creatures. Now, here is the nub, as southern Britain and nearby continental Europe, were considered to be under the sea during the dinosaur age, it is natural that marine reptiles such as the ichtyosaur, and their stomach contents, would have been part of the remains preserved in coprolite nodules (there are some good images to compare with the wiki article).
The Greensand ridge runs from Tring in Hertfordshire (at the foot of the Chilterns) to Cambridgeshire and East Anglia, running adjacent to the chalk exposures. They are thought to have originated from fossils that had eroded out of Jurassic clay formations, subsequently redeposited in the sand. Vast fortunes were made by landowners (which included Cambridge colleges). In 1870 coprolite was found in proximity to the Gault Clay formation in Bedfordshire and Buckinghamshire (assumed to have been laid down by a marine geography). Coprolite was dug out of the ground at places such as Cheddington and Ivinghoe, Edlesborough and Eggington, Stanbridge and Barton le Clay, and conveniently the Grand Union Canal had been cut through this locale. Coprolite from here was sent by canal barge to Wolverhampton and turned into fertiliser – known as 'superphoshate' (which can still be bought in any garden centre). The greensand ridge forms a scarp above the Oxford Clay formation that is now Milton Keynes, and coprolites at the lower reaches of the sand formation were exploited between Little and Great Brickhill. They were a distinct layer, as in the Gault Clay, and this has vexed your geologist to some extent as the clay formations are widely regarded as representing former marine environments. From a magnification in an eyeglass this may appear to be a reasonable deduction, as marine fossils can be seen as part of the mix. In a big picture, it is not quite as simple as the clays of lowland England look very much like a lot of geology has simply been washed away. Where is the geology between the Jurassic clays and the present? It is missing from the landscape.
It is now thought most coprolites come from marine reptiles or even from fish which fed on smaller prey. These produced lots of phosphate in their droppings. However, terrestrial reptiles (dinosaurs) are also part of the picture – in droppings and as fossilised bone and bits and pieces. The idea of a former marine habitat being dominated by terrestrial animal life was obviously a problem – and this part is now underplayed. So, was southern Britain covered by the sea, or not. Difficult to say. The Expanding Earth people would have to see it otherwise – but the idea of Pole Shift would embrace the sea exchanging places with the land, and vice versa. In mainstream the sea bottom has been raised by tectonic forces – with Plate movement and the collision of plates being the source of friction. It is thus a geological fundamental that the Jurassic and Cretaceous periods represent a marine environment – dinosaur dung is an unwanted guest. If they conceded in one place it would open a can of geological worms, so to speak, as we have the supposed shallow sea formation that ran right through the middle of N America (with plenty of evidence of marine fossils). It is a fundamental of American geology that this formation represents a marine environment – and it survived for millions of years. Might this formation also have been transitory – evidence of a catastrophe that involved the ocean sloshing across a continental land mass?