CHAPTEE VII. 



THE OLD BED AND CARBONIFEROUS PERIODS. 



I. THE OLD RED SANDSTONE. 



THE system of Silurian strata in the Malvern region was brought 

 to an end by means of great disturbance of the levels of the earth's 

 surface. These were not confined to the district itself, but were 

 so extensive in their operation that their influence was felt over 

 a great part of the circumpolar regions of the north. By their 

 operations some oceanic basins were dried ; others filled with enor- 

 mous loads of fresh sediment brought from distant shores and 

 transported in new directions ; old forms of oceanic life ceased ; 

 new forms were introduced; all the physical associations were 

 changed, yet with few or no marks of local violence. 



In the Malvern district these changes are observed; they are 

 not very sudden ; the old sediments are somewhat gradually mixed, 

 or else found to alternate with the new deposits ; the old life dies 

 out by degrees, and before it is quite exhausted some of the new 

 forms are introduced. The sea-bed underwent no convulsion ; 

 it continued to be sinking through some thousands of feet, and 

 was constantly receiving in comparative tranquillity layers of 

 argillaceous, arenaceous, and partially calcareous deposits. But 

 these were of a new order ; generally of a red or pale green tint, 

 the former colour being due to red oxide of iron, while the latter 

 may have been caused by deoxidation of sediments originally red. 

 This deoxidation may have been occasioned by decomposing veget- 

 able matter ; whether before the transport or after the deposition 

 of the sediment may be matter for inquiry. Analogies for either 

 supposition may be supplied from existing natural occurrences a . 



* The discharge of colour here referred to may be seen to have happened in many 

 flagstones of the old red series in Herefordshire and Monmouthshire, where it waa 

 well observed by Col. Sir H. James in 1842. Mr. Maw has lately investigated the 

 subject largely. ^ 



