By A. J. Juices-Browne, B.A., F.G.S. 



319 



an explanation of these I must direct attention to the sections. 

 Section 1 shows the natural order of the strata which lie beneath 

 Devizes. Beds of rock are not generally vertical masses, but layers 

 or courses which run one under another, and are continuous, hori- 

 zontally or obliquely, for a great distance underground. Thus 

 bed a in the diagram, which u called the Kimeridge Clay, and 

 comes to the surface between Seend and Poulshot, would be found 

 under Devizes if anyone made a boring down to the level at which 

 it occurs, and a geologist can generally estimate the depth at which 

 any such bed can be found. 



The other section before you is one through Morgan's Hill, and 

 shows the successive beds of Chalk of which it is composed, the 

 lowest of them resting on the same bed of green Sand which comes 

 to the surface round Devizes and Bishops Cannings. 



The rocks in the immediate neighbourhood of Devizes belong to 

 the Cretaceous System, and for the purposes of description they may 

 be dealt with under the following names, in descending order 



7. Upper Chalk. 3. Malmstone. 



6. Middle Chalk. 2. Gault. 



5. Lower Chalk. 1. Ironsands. 



4. Greensand. 



1. — Ironsands. The lowest beds of the system are the brown 

 pebbly Sandstones of Poulshot and Rowde, with the outlying patch 

 at Seend. The pebbles in these beds are chiefly small rounded bits of 

 vein-Quartz which have been derived from much older rocks that lie 

 to the west of Wiltshire. Fossils are rare in them, and they would 

 have been credited with few organic remains if Mr. W. Cunnington 

 had not been careful to collect from the cutting made for the road 

 up Seend Hill in 1849. This is an excellent instance of the useful 

 work which a local geologist can accomplish, and the geological 

 members of every local Natural History Society ought to consider 

 it their duty to record and collect from all such exposures while they 

 are fresh and clear. If they do not, valuable and interesting facts 

 are lost to science, for the banks become obscured with earth and 

 grass in the course of a few years, when the geologist who then 



