14 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 20, 



and bored to about 120 feet ; but the clay-seams gradually thin out, 

 in depth, as shown in fig. 3. The pipe-clay and stiff clay in some 

 places run down almost perpendicularly, as shown in bed 3 in fig. 3, 

 representing the appearance of having been partially washed away 

 by a stronger current than at first deposited the bed ; and, wherever 

 this occurs, the deposit lying on the bed so partially washed away 

 is of very much rougher texture — generally fine or coarse sand or 

 gravel. 



Here and there a smooth water-worn stone, generally of quartz, 

 but sometimes slate, is found imbedded in the clay. I^odules of 

 iron-pyrites, of aU sizes, from that of small shot to that of an egg^ 

 are in some places abundant. Detached pieces of lignite, too, are 

 very common — sometimes with the surface changed into mundic. 



The clay and accompanying beds at the Decoy rest against the 

 Greensand hills surrounding this portion of the basin ; and the strike 

 of the beds forms a segment of a circle, somewhat conformable in 

 direction to the shape of the hills. 



Fig. 4. — Section of Clays and Lignites at Aller. Scale ^th inch to 



a fathom. 



1. " Head" of gravel 



2. Sand. 



3. Muddy clay. 



4. Lignite. 



5. Clay. 



6. Lignite. 



7. Clay. 



8. Tljyee seams of lignite, separated by fine clay. 



9. Fine clay. 



10. Eough clay. 



11. Fine clay. 



12. Eough clay with gravel. 



13. Eough sand and muddy clay. 

 The beds dip to the East. 



Fig. 4 shows a section* of the potter's clay and lignite-beds at 

 AUer. Here the lignite, separated by beds of clay, is more developed 

 than at the Decoy. No fine pipe-clay has been found at Aller ; but 

 underlying the beds shown in the section, and occupying the posi- 

 tion of the pipe- clay, are rough clays, highly stained with ochre, all 

 having an eastern dip. 



It will be observed in all the sections here given that the dip of 

 the beds increases from the sides towards the centre of the basin ; 

 and this I believe to be generally the case throughout the deposit. 



The clay-beds throughout the deposit show no sign of disturbance 

 by slips or faults ; they seem perfectly unaffected by any other power 

 than that of water. 



* Constructed from numerous observations whilst superintending the works 

 during several years. 



