1864.] Jenkins on Brackish-water Fossils of Crete. 415 
the wall of a series of marine beds containing newer Pliocene fossils ; 
so that the fresh-water beds must be the older, and as, granting the cor- 
rectness of the former argument, they have been proved to be newer than 
the Upper Miocene, they must, in that case, hold an intermediate 
position, and on these grounds they have been termed Older Pliocene. 
Thus far, excluding the scepticism, I have followed Professor 
Forbes and Captain Spratt, who enunciated the above (apparently) con- 
vineing proof of the age of the Cos and Xanthus fresh-water beds in the 
‘Travels in Lycia’ already referred to. From a very brief considera- 
tion of the argument, the principle on which it is based will make 
itself apparent to everyone. The object is to fix a limit in both 
directions to the age of the strata, or, to use the original terms, to find 
an ‘ante-date’ and an ‘ after-date,—a process often resorted to by the 
inquisitive in their efforts to discover the ages of their friends ! 
If we inquire a little more closely into the basis of the argument, 
namely, that the inclined position of the marine strata is suggestive of 
their greater age (which is altogether assumed), we shall find, on 
reference to the section given below, that they dip the wrong way !—and 
thus a doubt is cast upon the whole of the reasoning. The following 
explanation will make my meaning clear: suppose the Scaglia and 
Macigno to be more or less horizontal, and the marine formation to 
be deposited conformably on it, then suppose the valley to be formed 
by the elevation of the Scaglia on each side, and to be rendered deeper 
by the erosion of the marine strata, it is evident that the remaining 
patches of the marime formation would dip conformably with the 
Scaglia, not at nearly right angles to it, as in the following section :— 
Section across the Valley of Xanthus.—(After Forbes and Spratt.) 
E, We 
S 
X 
Se 
Cate 
SS = 
€ 
@ Marine sandy strata (Miocene), dipping from the centre of the valley- 
b. Conglomerate. c. Marl (freshwater). d, Macigno, 
e. Scaglia (Cretaceous) dipping towards the centre of the valley. 
On the other hand, if the Scaglia were upheaved, as it evidently was, 
before the deposition of the marine beds, it is quite impossible that the 
latter could have been deposited horizontally and afterwards tilted up, 
because the Scaglia must have been affected at the same time; and if 
we assume that its dip was lower when the marine beds were formed, 
the latter must have been deposited almost vertical, which cannot be 
credited for a moment; and if the marine Tertiaries were deposited 
in a horizontal position, the Scaglia must formerly have been nearly 
vertical. Indeed, it is evident that the apparent dip of the marine 
