558 MK. H. H. AENOLD-BEMROSE ON THE [^^?« 1899, 



Specimens 



V 1056, 6 feet below 1011 

 T 1057, above 1009; 

 R 1058, below 1009; 

 N 1060 ; 



X 1061 ; 



1068, between X and Y ; 

 1066, from the bottom of 

 the quarry, 



are t ii fa ceous limestones, more or less alike and much more de- 

 composed than A, B, C, & D. They contain traces of fossils ; the lapilli 

 are generally altered to calcite, and felspars are rare in them. 

 Specimen 1061 contains Girvanella, and in 1066 a few angular 

 fragments of quartz are seen. 



P 1059 is a coarsely laminated tuff, 5 feet thick. It consists 

 of more or less rounded fragments of igneous rock, limestone, and 

 fossils. The lapilli are either vesicular and non-crystalline, or 

 contain pseudomorphs of felspar and olivine, and are then similar to 

 those in 979, but in a much more advanced stage of decomposition. 



M 1062, 1063, and 00 1064 are in so decomposed a state 

 that from a hand-specimen it is impossible to tell whether any of 

 them is a piece of a lava-flow or a block of lava from a tuff-bed. 

 The thin slices examined consist of a massive rock, with pseudo- 

 morphs of felspar and perhaps of olivine, which when in afresh state 

 was probably similar to the rock of which the lapilli in 979 were 

 formed. 



In addition to the igneous rocks, two specimens of calcareous 

 grit were examined. 



F 1065 consists of angular fragments of quartz in a calcite-matrix. 

 These minerals are present in nearly equal proportions. There are 

 also a few fragments of a slightly dichroic mineral, which is probably 

 mica. The slice is traversed by veins of crystalline calcite. This 

 specimen is very similar to a calcareous grit occurring in the Kinder 

 Scout Grit, at Crich (Derbyshire), which, in addition to quartz, 

 contains a few felspars and a small quantity of mica. 



Specimen 1067 is a similar rock, containing fewer quartz- fragments 

 and traces of fossils in a partly calcareous matrix. In these speci- 

 mens the quartz-grains are always angular, generally isolated one 

 from another, and have not a crystalline outline like those which 

 are found in the Mountain Limestone. The quartz often contains 

 inclusions, and apparently is not a secondary product. 



3. Summary and Conclusion. 



The igneous rock in the quarry is either a volcanic agglomerate 

 filling a vent, or a thick deposit of very hard, coarse, and tumultuous 

 tuff, which is probably not far distant from a vent. The section in 

 the brook consists of limestones, some of which are tufaceous, with 

 at least two beds or intercalations of tuff. This proves conclusively 

 that there was volcanic action contemporaneous with the deposition 

 of the limestones. 



The lapilli are of two kinds — the originally glassy vesicular or 

 palagoaitic type, without crystals, and the basaltic or doleritic type, 



