PT. 2 .] 
Wynne. Surat CoUcdorale, 
29 
lying one upon another, and beds passing from one texture to the other without any hind 
of sequence, but at several places where from the considerations given above we might infer 
an approach to the upper portion of the group visible in this country, there is a predominance 
of the red lateritic beds as the trap rocks first become visible in ascending the streams. 
Connecting these different points of eminence there would seem to be a zone of ferruginous 
traps either among the highest trap beds of the Surat district or along the border of the 
Nummulitie series which rests unconfonnably upon them- 
This zone seems certainly to belong more to the traps than anything else. As an instance, 
however, of what may he a somewhat analogous occurrence, I may mention that at the 
unconfomiable junction of the old red sandstone and silurian formations in the interior of 
the south of Ireland, the silurian rocks over large districts and to a considerable distance 
from their boundary, hut always apparently in consequence of the vicinity of the old red, 
change from gray to red and are highly ferruginous; in some places containing veins of 
haematite; this ferruginous appearance increases as the unconformable boundary limit is 
approached notwithstanding any circumstances of dip or strike in the (silurian) roelcs of 
which it is quite independent; and so plainly is it marked that upon observing it I used to 
know I was approaching the old red boundary. It has generally been attributed to infiltra¬ 
tion from the overlying ferruginous red rocks, and as the numnmlities here contain laterite 
beds near their base similar causes may have produced like results. 
The Nmnmulitic series is the next geological sub-division in the ascending order, 
resting unconfonnably upon the traps,* and spreading in gentle undulations under a largo 
portion of the district. It consists of a very varied series of beds comprising hard lateritic 
ferruginous rocks, coarse conglomerates, dull yellow earthy limestone, sandy and clayey beds, 
and beds of loosely cemented gravelly conglomerate. The following table compiled from 
various sections will show the general features of the exposed portion of the series with its 
preponderance of sandy and gravelly beds above and ferruginous ones near the base :— 
Conglomerates, sandstones and hard calcareous breccia. 
Yellow limestones, sandy and gravelly conglomerates and shales (Oyster shells and 
Balanidte). 
Calcareous sandstones, gravelly conglomerates, sandy limestone and shales (fossil 
wood, shells and spines). 
Sandy conglomerate, sand layers and ferruginous partings. 
Calcareous concretionary clay and pale yellow sandstone (hone fragments). 
Sandstone and clays (sandstone containing plant fragments). 
Agate conglomerates. 
Limestone (with Nmnmulites). 
Stratified ferruginous conglomerates and sandstones and sands. 
Stratified ferruginous sandstones, blue clays and variegated beds. 
Yellow ochrcous sandy clay, bluish and pale lilac clay. 
Shales, sands, clays and sandstones. 
The above list indicates the general features only, and is not a detailed representation of 
any one particular succession. Calcareous beds are often met with, but though these here 
and there become represented by thin hands of limestone, it was only in one locality (the 
country about Turlteesaur) that this was observed to occur in sufficient quantity to occupy 
a large space of ground. 
From the position of this series it is difficult to arrive at an estimate of its thickness, 
which must, however, be very considerable, although the angles are so frequently low, for 
sections with a vertical thickness from one to three hundred feet may be seen in many of the 
streams. Many of the beds are highly fossiliferous; some are largely made tip of nmnmulites, 
others of the separated valves of Jialanidie, some contain a number of univalve and other 
shells with which the teeth of sharks, segments of the carapace of a turtle, and of large ribs 
* The evidence for this assertion ia but small, only one junction, or rather very near approach to a junction, is 
seen. Here the rocks have the appearance of unconformity, but in other places where the two formations occur at 
short distances from each other there is reason to believe that, the ground is traversed by faults. The deduction is 
made from the occurrence of conglomerates in the upper series containing agates derived apparently from the 
traps, also from local appearances and observations upon the same rocks made at a distance from this district. 
