J. H. B. Jenkins — Analysis of London Clay. 265 



. The Devonian formation, which constitutes the larger part of the 

 islands, was carefully surveyed, and fossils discovered in several new 

 localities. The stratigraphical and tectonic conditions, on the West 

 Island especially, proved to be of much interest. My most important 

 task, however, was to solve the question of the supposed occurrence of 

 Permo-Carboniferous layers of the Gondwana type. Some fragmentary 

 plant fossils, collected in 1902 during the Swedish Antarctic expedition, 

 were described by Professor JS'athorst in Stockholm under the name of 

 Phyllotlieca sp., and compared with a species from the Glossopteris 

 flora, but owing to the fragmentary condition of the specimens their 

 determination remained doubtful. I have now been able to settle the 

 question. Possils, principally leaves of Glossopteris, occur in many 

 places, and it is evident that the whole southern part of East Falkland 

 south of Wickham Heights belongs to the Gondwana system. At the 

 base of the Glossopteris series I discovered a Boulder-clay formation 

 containing blocks of stone apparently of Glacial origin, which un- 

 doubtedly corresponds to the well-known moraines from other parts of 

 Gondwanaland. 



Of more recent formations, an interesting Porest-bed, discovered on 

 West Point Island by Mr. A. S. Felton, was made an object of special 

 investigation. The bed, which contains great quantities of large 

 trunks, is covered by old ' flowing soil,' and is probably of Pre-glacial 

 age. After having been worked out, my collections will give 

 important information as to the phyto-geographical and climatological 

 conditions of these islands during the early Quaternary period. I have 

 also paid attention to the other Pleistocene deposits, as well as to the 

 question of changes of level, supposed to have occurred in the latest 

 period. The result of these researches cannot be communicated until 

 the observations and collections have been thoroughly studied. 



VII. — An" Analysis of London" Clay. 

 By J. H. B. Jenkins, F.C.S. 



THE sample analysed was derived from a well-boring made at 



East Ham by Messrs. C. Isler & Co., Avho gave the following 

 table of the strata passed through : — 



Thickness. Depth, 



ft. in. ft. in. 



Soil Mould 3 3 



Eiver Gravel ... Ballast 14 17 



-r n p, I London Clay 59 76 



l^ondonOiay •••{ Sand, Shells, and Pebbles ... 10 86 



Woolwich Beds 



and 

 Thanet Sand. 



fBlue Clay and Shells 10 96 



Mottled Sand 6 102 



Sandstone 5 107 



Gray Sand 16 123 



Lire Gray Sand 30 153 



Dead Gray Sand Loam ... 26 6 179 6 



Green Coated Flints 6 180 



Chalk and Flints 120 300 



The sample was taken from the stratum of clay between 17 and 

 76 feet below the surface. 



