22O Upper Greensand. 



geological date, not later than its successor the Upper 

 Greensand. 



It would be a great comfort to a proportion of the 

 geological population, if the different formations were 

 as clearly distinguishable on the ground, as they are on 

 a map, by different colours, aided by numbers or letters 

 for the use of the colour-blind. If to this, in the 

 economy of Nature, it had so happened that no species 

 had been permitted to stray from its own formation 

 into the next in succession, the benefit would have been 

 much enhanced, for to those with keen eyes for form, 

 the finding of any single fossil would be sufficient to 

 mark the place in the geological scale of any given for- 

 mation. Then we should have a perfect and orderly 

 symmetrical accuracy of detail, so that he who runs 

 may read. But it so happens that this is not the case, 

 for Nature loves variety, and performs her functions in 

 various ways, and thus it happens that in certain cases 

 the dividing lines between two formations, if we follow 

 them far enough, are sometimes difficult to determine. 

 Of these unruly formations in England the Upper 

 Greensand forms one, in its occasional physical rela- 

 tions to its neighbours, the Gault below and the Chalk 

 above. 



THE UPPER GREENSAND in the West of England 

 appears in great force, forming part of the strata that 

 extend from the coast between Lyme Regis and Sid- 

 mouth, northward to the Black Down Hills, south of 

 Taunton. West of the estuary of the Exe, it forms, in 

 two outlying patches, the broad-topped hills of Great 

 Hal- don and Little Hal-don, and south of the angle of 

 the Teign, near Newton Bushell, there is another outlier 

 on Milber Down. These lie so near the main mass, and 

 approximately are so much on the same level, that they 



