1914-15.] Structure of the Chalk in the West of Scotland. 297 
XXV. — Notes on the Structure of the Chalk occurring in the West 
of Scotland. By the late William Hill, of Hitchin, F.G.S. 
Communicated hy Professor D’Arcy W. Thompson. 
(MS. received June 12, 1915. Bead June 28, 1915.) 
The general succession of the Cretaceous rocks discovered by Professor 
Judd on Morvern, along the shores of Loch Aline, Argyllshire, and in the 
Isle of Mull may be briefly summarised : — 
I. Sandstone and white marls with plant remains (High 
Cretaceous or Early Eocene) ... 20 ft. 
II. White indurated chalk with bands of flints, Belemnitella 
mucronata and fragments of Inoceramus, some beds 
of glauconite chalk at the base , . . 10 ft. 
III. White sandstones without fossils . . 30-100 ft. 
IV. Glauconite sands passing into dark green glauconite 
sands or calcareous sandstone, Pecten asper and 
Exogyra conica ..... 20-60 ft. 
The lowest bed of glauconite sands (IV), says Professor Judd, ‘‘ unques- 
tionably represents the Cenomanian or Upper Greensand, and in its 
mineral characters greatly resembles the equivalent strata in England and 
Ireland.” * The white sandstones (HI) are regarded as the equivalent of 
the Middle and Lower Chalk of England ; while the white siliceous chalk 
with flints, with a bed of nodular and glauconitic limestone at its base, 
followed by II, are regarded as representing the Upper Chalk zone of 
B. mucronata. *[* 
In the “ Geology of the Small Isles of Inverness-shire ” I rocks of Creta- 
ceous age are thus referred to : “ Bocks of Cretaceous age are represented in 
Eigg by some two feet of hard white calcareous sandstone . . . underlain by 
a thin deposit of glauconitic sandy mud of older date.” “ This thin remnant 
of whitish-calcareous sandstone, with chalky inclusions and siliceous patches 
and nodules, often of a dark-grey colour, rests upon Oxfordian strata. 
* “All Cenomanian” — A. J. Jukes-Browne, in litt. after reading the MS. of this paper. 
t “ Professor Judd, “ On the Secondary Books of Scotland,” vol. xxxiv, 1878, 
p. 729. 
f “Geology of the Small Isles of Inverness-shire,” Memoir of the Geol. Survey (Scotland, 
Sheet 60), 1908, p. 33. 
