14 



THE BRITISH ISLES. 



Farther west still, amongst the many bays which indent the coasts of Devon 

 and Cornwall, the foremost place belongs to Plymouth Sound, which ranks with 

 Chatham and Portsmouth as a great naval station. 



If we now turn to a consideration of the principal features of Ireland, we 

 shall find that they differ essentially from those presented by the more favoured 

 sister island. Less varied in its contour, it exhibits likewise greater simplicity in 



Fig. 8. — Plymouth Sound and the Hamoaze. 

 From an Admiralty Chart. Scale 1 : 150,000. 



^1 t:"'t.r,7.'^^/?r^) '^ 



-/« 







"^^ (S 



23 .>^ "■■■^- 



5 ^2 V S^-^^^t^ 



9 jVt.'o "« «5* 6 



7 i ,, ■< 





t^"" '■'' {ii'p^— : 



2 Miles. 



its geological structure. Broadly speaking, it may be described as consisting of a 

 great central plain of carboniferous limestone, stretching across from sea to sea, 

 and bounded in nearly all directions by mountain masses composed of the most ancient 

 geological formations.* The highlands of the north-east, north-west, and west 

 consist of the same crystalline and Silurian rocks which are so extensively developed 

 in Scotland. The south-eastern highlands likewise consist of Silurian strata pene- 

 trated by granite, and overlying Cambrian rocks, thus repeating the features which 



* E. Hull, " The Physical Geology and Geography of Ireland." 



