132 REPORT — 1861. 



their bedding, -which is nearly vei-tical, unchanged. The condition of theise rocks is 

 very similar to that of the same rocks outside the granite area ; and it is a point of 

 great interest to determine how they got there. The solution of this offered by the 

 author of the pajier was that the whole of the rocks had been originally stratified, 

 and had been subjected to some actions which are termed metamoi-phic. ' The result 

 of such action was to convert some into granite, some into gneiss, and some into cry- 

 stalline limestone and mica-schist, withoutverymuch altering their relative positions. 

 The possibility of granite being produced by other means than simple heat seemed to 

 them to be proved by the occurrence of felspar in quartz veins, which are usually 

 admitted to have been filled by means of infiltration. The author stated that there 

 were several points in connexion with these granites which showed a close relation 

 between them and the granites of Norway. The whole question required a careful 

 chemical and mineralogical examination, which could not be concluded for some 

 time. Among the types of rock found in Donegal is a syenite, the felspar of which 

 is oligoclase. The origin of this rock the authors are disposed to attribute to the 

 addition of limestone to the granite. A similar syenite occm-s at Carlingford, but 

 contains anorthite, a felspai- which would residt from the admixture of a larger 

 quantity of limestone than is necessary to produce oligoclase, and has been proved 

 by Professor Haughton to have such an origin. The anorthite syenite never occurs 

 unless limestone is present in large excess, which is not the case in Donegal. In 

 conclusion, Mr. Scott mentioned that the district described by him was very rich in 

 minerals, some of which were extremely riire, and that he entertained no doubt that 

 a more careful examination would largely increase their number. 



On the Elswortli Rod-, and the Clay above it. By Haret Seelet. 



The Elsworth rock is a limestone somewhat oolitic and pjTitous, divided by a 

 dark clay into upper and lower beds characterized by different fossils. At the vil- 

 lage of illswoi-th the entire thickness is not more than 14 feet, a thickness which a 

 well-sinking three miles S.S.W. showed it still to retain. The dip bein"' in this 

 direction, and of about 1 foot in 200, it followed that another stone band foimd at 

 St. Ives, 4^ miles north, would be 130 feet lower do^^^l. This rock, at a point 

 midway between St. Ives and Elsworth, was found in a well to be some 5 feet thick • 

 at St. Ives what remains of it is rather thicker. It is more earthy than the Els- 

 worth beds, has similar fossils, and is often divided b}' a thin parting of clav. At 

 Bluntisham, two miles N.N.E. of St. Ives, the Elsworth rock is again met with 

 the St. Ives rock therefore coming up in a saddle. Another rock is found at St. 

 Neots. As the St. Ives rock occurs at Papworth, little more than two miles west 

 of Elsworth, and St. Neots is six miles west of Papworth, this stone band is re- 

 garded as gi'eatly below the other beds. A similar conclusion would be dra^v^l 

 from the fossils of the adjacent clay. At Tetwoiih, seven miles S.W. of Elsworth 

 and therefore above the Elsworth rock, a thin limestone of a foot and a half was 

 found. 



These rocks mark zones in the clay all distinguished bj- difii^ring groups of fossils : 

 the St. Neots zone hus Ammonites l}tmca»i, A. spinosiis, A. atJddm, A. cormiatus, &c. • 

 the St. Ives zone A. Evgenii, A. Maria, A. cordatm, A. Goliathiis, Sec. ; in the next 

 zone are A. Baheanus and A. alternans ; and in the Tetworth zone A. Achilles, Be- 

 lemnitcs crcentricus, Lima j)ecfinifonnis, Grypha:a dilatata, Ostrea deltoidea, &c. 

 Above this latter zone no stone bands are known, there being a great thickness of 

 clay which appears to pass gi'adually into the Kimmeridge clay, the coral rag beino- 

 wanting. But as there is not the iLsual break in life, but a blending of the fossils 

 of two clays hitherto distinct, and with them some fonns of the coral rao-, the 

 coral rag was still present as a period, though under a new fomi. Provisionally 

 this stratum is called the Tetworth clay*. The Elsworth rock is at its base • ite 

 upper limit is unknown ; in it are very few new and peculiar forms. 



The Elsworth ror-k abounds in fossils, a careful examination of which showed it 

 to bo rather the up[)ermost part, of the Oxford clay than a representative of the 

 calcareous giit at the base of the Tetworth clay. A few of the species are — Am- 



* At the Meeting it was called Bluntisham clay. 



