Geologists' Association. 473 



not very fossiliferous. The Ironstone section was poor compared with some the 

 party had visited during the previous day, nor does it appear that tliere are any 

 very valuable quarries in the Northampton Iron Sand hereabouts. After luncheon 

 the party drove through Stamford, which might be described as the Stone town, 

 or city of Churches, and up the hill on the north to the top of Stamford Field. 

 From the level of the Welland to this plateau there is a rise of about 200 feet vertical, 

 made up of the following beds in descending order : — 



S' Cornbrash- — ^just a cap on the summit. 

 Great Oolite Clay — not exposed. 

 Great Oolite Limestone— base just seen. 

 Upper Estuarine Series — Torkington's Brick-pit. 



T r • i Lincolnshire Limestone — many quarries. 



Inferior J j F ( ' i 



Oolite. I -c- r su rm \ Northampton Sand. 

 \ r errugmous l^eds j ^ 



Upper Lias Clay — a few feet. 



Torkington's Brick-pit presents an interesting section of about 25 feet— principally 

 variegated clays, referred to the Great Oolite, and traced by the Geological Survey 

 to the horizon of the Stonesfield Slate. It is known in Mr. Sharp's Memoir as the 

 "Upper Estuarine," is of variable composition and thickness, frequently sandy, 

 and is always found in this district underlying the Great'Oolite Limestone. Several 

 of the clay bands are pierced by vertical carbonaceous markings, and are also 

 shelly ; some fossils were picked up, but their condition was such as to render 

 them very difficult of identification. Modiola imbricata and other bivalves were 

 amongst them. The brackish-water genus Cyrena was found. The last two 

 excavations visited within the Stamford area, north of the town, are quarries in the 

 Lincolnshire Limestone. In Simpson's Quarry, from which is obtained some of 

 ihe best building-stone in England, and the beds of which are geologically the 

 same as those at Ketton, viz. the upper part of the Lincolnshire Limestone, the 

 blocks obtained are of great size, very uniform in their composition, consisting of a 

 fine-grained Oolite, and ring like a bell when struck with the hammer. Above 

 the limestone, occur about 15 feet of the Upper Estuarine Clays, with a ferru- 

 ginous band towai'ds the base, as is usual. About the line of junction, there is 

 often a thin band of a white friable aluminous earth, somewhat of the nature of 

 Scarbroite. In Tinkler's Quarry, still lower beds of the Lincolnshire Limestone 

 are observed, including a Shale-bed, said to contain many shells, well-preserved, 

 but crushed. Below this is a hard, blue-hearted Limestone, containing coral, 

 Nerhicea, and many other fossils — the "Stamford marble." Some fragments of 

 coral were obtained by the party, but neither here nor in the other quarry were the 

 spoils of the Lincolnshire Limestone of much consequence. One or two casts of 

 Natica Leckhaniptoiiensis, a specimen of Lucina Wrightii, and a doubtful Trigonia 

 were about all that came under the reporter's notice. These and adjoining quarries 

 have, however, been watched for a number of years by careful palseontologists, 

 and notably by Mr. Sharp, Mr. Bentley, and Prof. Morris. It is in their collec- 

 tions, and especially in that of Mr. Sharp, thai the evidence of the geological 

 horizon of the Lincolnshire Limestone must be sought. For many years there 

 was a general inclination to class these important beds (the Lincolnshire Lime- 

 stone) with the Great Oohte ; but the National Survey has ultimately decided to 

 place them at the top of the Inferior Oolite formation, of which throughout the 

 county of Lincoln they form by far the most important member. Notwithstanding 

 their apparent poverty of fossils in the Limestone quarries of Stamford, no less 

 than 315 forms have been noted by Mr. Sharp from all parts, including the CoUy- 

 weston Slates, a local group at the base of the series. One of the most remarkable 

 features of this extensive fauna is the scarcity of Cephalopoda, especially of 

 Ammonites. Am. terebratus, Phillips {tnaa-ocephahis, Schlot., Herneyi, Sozu.), 

 marked as occurring, is a characteristic Cornbrash form. Am. Mu7'chinsonce and 

 subradiatus, however, are the two other species quoted, and these represent very 

 low zones of the Inferior Oolite. 



The party now driving rapidly through Stamford, mounted the great plateau on 

 the south side of the Welland, on which is situated the village of Collyweston, 

 some four miles distant. 



The Slate is a sandy laminated limestone, very hard, and sometimes blue-hearted, 

 lithologically it is not unlike Stonesfield slate. As the Geologists' Association 



