GEOLOGY 



Nemacanthus filifer Hybodus reticulatus Ceratodus altus 



Saurichthys acuminatus Acrodus minimus Gyrolepis tenuistriata 



Hybodus minor Sargodon tomicus Ichthyosaurus platyodon 



Most of these occur also at Barnstone. In the deep boring at 

 Owthorpe 14 feet of black paper-shales were recognized, and at South 

 Scarle 1 5 feet of strata have been referred to the Rhaetic. 



From these observations can be seen the vast difference lithological 

 and pafceontological between the Keuper and the Rhaetic. Another 

 point comes out from the consideration of position and thickness. The 

 Black Shales are remarkable for their constancy in both respects. 

 Throughout their range they remain not far from the 200 feet contour 

 line. They are not dependent on local conditions in fact the bone 

 beds of the period, though thin, are of European extent ; the fossils are 

 named from those of Germany and the Alps. The fish remains are all 

 parts only, and the bone beds being aggregate deposits, they represent the 

 species killed on the introduction of the new conditions. 



THE LIAS. The Lower Lias is the only part of the formation to 

 enter the county, and of this we have only information about the zones 

 near the base. It follows the Rhastic in due course with conformable strati- 

 fication and is made of similar material, the chief change being in the fauna. 

 The lowest beds belong to the Planorbis zone and consist of ' finely lamin- 

 ated shales interbedded with layers of fine grained argillaceous limestone.' 

 They are worked for hydraulic cement at Barnston, Granby, Elton, Cot- 

 ham, Coddington, Collingham and Balderton. At Barnston there are 

 ten bands of limestone in 20 feet of strata, in one of which a fine Ple- 

 siosaurus skeleton has been found. In one of the quarries at Coddington 

 another saurian skeleton was found and buried in the fallen rubbish. At 

 Elton there was found, prior to 1719, the hinder part of an Ichthyosaurus 

 skeleton, the stone containing it being turned fossil-downwards by the 

 side of a well. In that year, on turning up the stone, it was re-dis- 

 covered and sent by the rector of the parish to Dr. Stukeley, who figured 

 it in the Philosophical Transactions, vol. xxx. as ' a rarity the like whereof 

 has not been found before in this island.' It was in fact the first British 

 fossil reptile skeleton brought to the notice of the scientific world. Near 

 Gotham eight bands of limestone occur in 1 3 feet of strata with Ichthyo- 

 saurus tenuirostris. Saurian skeletons or remains have been found also near 

 Corthingstock. These beds thus well deserve the name assigned to them 

 in the south of England ' The Saurian Beds.' At Balderton a coral, 

 Monthrualtia haimei, has been found. The ordinary mollusca from the 

 zone, including the characteristic ammonite Psiloceras planorbe and 

 fourteen others, are widely distributed. 



The higher zones are probably present but are generally covered 

 by superficial deposits, especially in their southern range. In the east 

 the Angulatus beds contain nodules occasionally fossiliferous, and the 

 Semkottattts beds are inserted on the map, being recognized by containing 

 ironstones. The fossiliferous portion once exposed at Red Mile is beyond 

 the limits of the county. 



