Geologists' Association. 381 



in the third and fourth centuries, but its resources had remained 

 dormant until about twenty years ago. The |;Lower division of the 

 Northampton Sand is abundantly fossiliferous in bands and patches, 

 and contains Corals, Ammonites, large Nautili, Belemnites, Echino- 

 dermata, Lamellibranchiata, and Gasteropoda, including many new- 

 forms, among which are — Lima Sharpiana, Eth., X. deltoidea, Eth., 

 L. Dustonensis, Eth., Trigonia Sharpiana, Lycett, etc. The Upper 

 division consists of a white sand, sometimes intercalated with 

 patches of blue clay, and containing a peculiar plant-bed, consisting 

 of horizontal layers of super-growth overlying a bed of vertical 

 root-perforations. This division exhibits estuarine characteristics, 

 and has been termed by Mr. J. W. Judd, F.G.S., the "Lower 

 Estuarine" series. 



Nest in an ascending scale is an important formation (only 

 recently defined), consisting of beds of Oolitic and Marly lime- 

 stones. It attains in Lincolnshire to a thickness of 200 feet, and 

 has hence been designated the " Lincolnshire Limestone." The 

 fossil contents indicate that these beds are Inferior Oolite : they 

 constitute the uppermost group of the Inferior Oolite series in this 

 part of England. 



At the base of the Lincolnshire Limestone occurs, at CoUyweston, 

 Easton, and some other places, a calcareo-arenaceous band, which 

 upon exposure to frost splits into slates in the planes of its finely- 

 laminated stratification. This slate is of a cream colour ; it was in 

 ancient times the prevailing roofing material of a wide district, and 

 has been of late years much used for church work. The slate-band 

 is highly fossiliferous, and has yielded, among new forms, a beauti- 

 ful winged univalve, Pterocera Bentleyi, Mor. and Lye. ; a small 

 lobster, PseudophjUia ; and a unique star-fish, Astropecten Cottes- 

 woIdicB, var. Stamfordensis, Wright. Limestone beds occur above 

 this slate band: the lower being for the most part marly ; some bands 

 yielding a pure cream-coloured soft stone, well adapted for fine 

 interior work ; others a good rough building-stone, and all lime. 

 Above the marly beds are the beds of the well-known " free- 

 stone " quarried at Weldon, Ketton, Casterton, Ancaster, etc. It is 

 from the peculiar texture of this stone that the term " Oolitic " (so 

 inappropriately applied to the great series of formations bearing 

 that name, and which comprise beds presenting various and fre- 

 quently opposite petrological characteristics) has been derived. The 

 stone is composed entirely of small egg-shaped grains, embedded 

 in a calcareous matrix. A polished section shows that each of 

 these grains consists of a minute siliceous nucleus inclosed in 

 a series of concentric calcareous films. The beds have yielded 

 the characteristic Terebratula fimbria of Sowerby. A very shelly 

 band occurs generally above the workable freestone, which was 

 quarried anciently (even in times as remote as the Eoman occu- 

 pation) at Barnack, and hence was called the " Barnack Kag." 

 Many of our most ancient cathedrals and churches were built of 

 this stone, which time has proved to have been most durable ; 

 but it has not been quarried for nearly 400 years. From the 



