UNFOSSILIFEROXJS SPACES. 
161 
flanks and minor undulations of the eleva¬ 
ted district which bounds the horizon. The 
interior of this area will furnish but little 
to attract the botanist^ in comparison with 
the upper formations. Vast ranges of the 
old rocks are destitute of the traces of or¬ 
ganic life, although belonging to formations 
in which fossils occur. 
The unproductive strata of fossiliferous 
formations may be compared to deserts, 
where the explorer derives an aching sensa¬ 
tion of wearisome loneliness, as one plain 
after another rises sharply to the horizon 
without a trace of a living creature. The 
frequent recurrence, and enormous extent, 
of sheets of sedimentary matter entirely 
destitute of organic forms, in immediate 
succession to other layers teeming with the 
exuviae of animals, or plants, is a phenome¬ 
non often encountered by the geologist. 
The writer was recently proceeding 
through an uninteresting portion of North 
Devon, where this observation is abundantly 
verified. For twenty-two miles the yellow 
roads lead over a succession of dull low 
hills, in the cuttings and banks 
o 5 
a coarse 
