482 PROFESSOR GEIKIE ON THE 
interstratified with the basalt beds, innumerable thin layers occur among the 
associated zones of sedimentary strata. The character of these tuff seams may 
be inferred from the following details of less than two feet of rock at Pettycur 
Point :— 
Tit A ‘ : ; ; : é 4 1°5 inch, 
Limestone, ; : , ’ , : ‘ 0:2 
Taft, -< . . , : : ; : Oa 
Shale, . F : : 3 aa : 025% 
ote : ; : : a; ' 7 Onl ren 
Shale and tuff, ’ ; Lede ; i : 1 O)E we 
Shale, . ; : J ; : ty Shap: 02-4; 
Limestone, : ; : . ‘ : Ieee 
Shale full of volcanic bet, : ; : : ,) SO toe 
Shaly limestone, : ; ; ‘ : : Ct aie 
Laminated tuffaceous limestone, . . s PiU wa 
Limestone in thin bands, with thin lamine of tuff ; . 0:o 
Granular tuff, F ‘ ; 5 0G \. 
Argillaceous limestone, with diffused buf ; : t O97 
Fine granular tuff, é ; s f : O- Taig, 
Avrgillaceous limestone, with diffused tuft : : . 15 nx 
Laminated limestone, ‘ : OL 
Limestone, with parting of Soa tuft in inate, : : 0:9 
Tuffaceous shale, ; : : : : ; ri 
Limestone, J : : : : : , OA oaee 
Shaly tuff, ; ; ) f ; ; L DREAD as 
Laminated limestone, . 2 . ; ; ; Cus. 
Toutt. os “e ? . : t ; 1 Ape 
21°65 inches. 
basalt. Now and then a sharp discharge of larger stones would take place, as 
in the case of the block described by me some years ago as having fallen 2 
crushed down a still soft bed of coal.* . 
These volcanic eruptions, however, did not sociale interfere with the 
larger physical changes in progress over the whole region. Thus the depron on 
“Geol. Magazine,” vol. i. p. 22. 
