57 
The succession of the deposits from the surface is :— 
(a) Ferruginous grit and sandstone constituting the overburden. 
(h) Marl bed containing a few nodules and with crystals of selenite. 
(c) Nodular beds consisting of septarian nodules in a matrix of marl, 
grey to blue in colour, plastic when damp, but very hard when 
exposed to the sun. 
This is the type locality of that subdivision of the Tertiary system in 
Victoria known as Balcombian. 
Although important in this instance, it is difficult to give the thickness 
of the ferruginous grit and sandstone which constitutes the overburden. The 
landslipped exposure at Mornington shows thicknesses varying between 
5 and 40 feet. At Kackeraboite and Ballark Creeks the thickness of the over¬ 
burden must be considerably over 40 feet. 
The thickness of the marl bed varies from 10 to 60 feet. This bed shows 
only at Balcombe Bay, but it probably exists at the other localities. 
The table of analyses gives a comparison of this marl with some used else¬ 
where in Victoria. 1 2 
Table I. 
• 
Marls from Ford’s Pit, Mt. Duneed. 
Balcombe Bay, 
Mornington. 
No. 1. 
Yellow Marl. 
No. 3. 
Underlying Clay. 
Blue Marl. 
Lime 
0'60 
032 
036 
(= Lime Carbonate) 
107 
0-57 
0 64 
Magnesia ... 
108 
0-98 
Small amt, 
(=Mag. Carbonate) 
2*26 
2 05 
. . . 
Phosphoric acid 
• • • 
• • . 
Trace 
Insoluble ... 
86-01 
78-64 
73-49 
The nodular bed is dealt with under two headings :— 
i. The matrix (marl) containing the nodules. 
ii. The nodules. 
I. A comparison of the marl containing the nodules with some used at 
other places in Victoria 1 and America 2 , and is as follows:— 
Table II. 
Winchester, 
Maryland, 
US.A. 
Marls from Ford’s Pit, 
Mt. Buneed. 
Balcombe Baj r , 
Mornington. 
Grice’8 Creek, 
Mornington. 
Greensand 
Marl. 
Sample from 
16tt. Face. 
White Marl. 
Blue to Qrey 
Marl. 
Blue to Grey 
Marl. 
Lime 
(= Lime 
Car- 
Nil. 
14-08 
45-78 
20-77 
5-33 
bonate 
• • • 
, . . 
25-12 
81 -75 
36-97 
9-48 
Magnesia 
( = Mag. 
Car- 
0-78 
1 97 
1 *51 
Trace 
Trace 
bonate 
• • • 
1-58 
413 
3-17 
• • • 
• • • 
Phosphoric Acid... 
0-13 
• • • 
Trace 
Trace 
Insoluble 
52-30 
60-61 
12-17 
33 24 
50-37 
The samples from Mornington were obtained from above the nodular layer. 
Cosmo Newbery 3 analyzed this marl, and obtained from 1 to 5 percent, of phos¬ 
phate of lime, which is equal to about from | to 2J percent, of phosphoric acid. 
1. Agricultural Journal of Victoria, vol. x.. p. 10. 
2. Maryland Geological Survey (Eocene), p. 53. 
3. Prog. Rep. Geol. Surv. Viet., No. ix, Lab. Rep., p. 179. 
