158 John H. Cooke—Fiint and Chert in Maltese Limestone. 
extent to which the beds were influenced by the river-waters which 
brought down detrital products from the surrounding continental 
areas. 
The following table shows the relative positions, and the more 
prominent characteristics of the sub-divisions. 
Formation. Sub-divisions. | Thickness. 
a. A greyish, fine-grained freestone. 15 to 20 feet. 
6. First seam of phosphatic nodules. 1 foot. 
c. A whitish, compact, fine-grained freestone. | 40 to 50 feet. 
: d. Second seam of phosphatic nodules. 1 to 2 feet. 
Globigerina e. A soft blue limestone with phosphatic nodules 
Limestone. irregularly distributed throughout it. 50 feet. 
f. A white, highly calcareous limestone with 
| flint and chert nodules. 30 to 50 feet. 
g. A coarse-grained yellowish freestone. 20 to 40 feet. 
h. Fourth seam of phosphatic nodules. 2 to 4 feet. 
It would be irrelevant to here consider these beds in detail ; 
T shall, therefore, simply regard the formation as being broadly 
divisible into three sections, 7.e. 
a. Deposits containing from 380 per cent. to 80 per cent. of 
carbonate of lime; the residue being principally made up of 
alumina with a small quantity of silica. Dr. John Murray con- 
siders this portion of the bed to have been formed on a descending 
sea-floor in about 300 fathoms of water, and to have been within 
the influence of river-waters and their detrital products. 
b. Deposits containing from 80 to 90 per cent. of carbonate of 
lime. Probably deposited in about 1000 fathoms of water. 
c. Deposits containing 70 per cent. and less of carbonate of lime; 
and consisting for the most part of the remains of comparatively 
shallow-water organisms. These were laid down on a rising sea- 
floor, and in about 3800 fathoms. 
The Globigerina limestones may, therefore, be considered as 
being a series of deposits laid down during a gradual but 
constant change in the position of the sea-bottom, the deposits in 
division b. having been formed about the time when the maximum 
depression was being attained, and at a considerable distance from 
any shore-line. 
In the lower parts of this intermediate division considerable 
quantities of siliceous concretions are found to occur in certain 
localities, of which the cliffs at Fommer Rih, the escarpments around 
the slopes of Uied Mars-el-Forn, Uied Sakkaja, and Uied Hempsia, 
and the quarries of Tad-dual, Tal Gauchi, and Inghieret furnish 
some of the most characteristic specimens. In none of the more 
impure varieties of limestone in either the upper or the lower 
divisions have any specimens been found. 
The concretions assume a variety of forms occurring sometimes 
as irregularly shaped masses of two or more feet in length, and 
from six to twelve inches in thickness, or as spheroidally shaped 
