474 TRANSACTIONS OF SECTION C. 
marked the original source of the Trent, as the Upper Trent Valley appears to 
be of more recent date. 
The Stour basin is likewise a combination. Streams descend south-west from 
Dudley to Stourbridge, and north-eastward from Clent to Halesowen. They 
are united by a succession of gorges four miles in length. This basin is a 
remarkable instance of extreme post-glacial denudation to a depth of 300 feet. 
The Halesowen streams represent the original headwaters of the river once 
flowing through Blackheath, Oldbury, and Smethwick. 
The Rea basin possesses three eastward-flowing streams successively diverted 
N.N.E. through Birminyham by a stream working back along the Rea fault. 
Two of these were captured in pre-glacial time, the third in consequence of 
glacial lakelet overflow. The present thrice-notched ridge at King’s Heath 
represents the pre-glacial land surface. The Middle Cole Valley is wholly post- 
glacial. The Lickey anticline has undergone elevation since the initiation of 
the Rea streams—i.ec., in post-Tertiary time. It is crossed by three waterworn 
gaps excavated pari passu with this uprise. The southernmost of these now 
drains into the River Arrow. 
The Warley Barr area is a region of Tertiary uplift, across which rivers 
occupying the old pre-Triassic valleys have excavated deep channels. All other 
streams in this area are very youthful. 
Conclusions.—The Trent drainage area has been subjected to excessive piracy 
and has steadily suffered loss. Its sole gain is that of the Penk at the expense 
of the Dee. The northern drainage is consequent on the formation of the South 
Staffordshire anticline, regarding the age of which it bears notable evidence. 
Speculations as to the former north-west extension of the Thames drainage must 
therefore be abandoned on reaching the area under consideration. 
5. On the Formation of Rostro-Carinate Flints. 
See Appendix, p. 788. 
6. On the Structure of the Lias Ironstone of South Warwickshire and 
Oxfordshire. By Epwin A. Waurorp, F.G.S. 
The ironstone of South Warwickshire and North Oxfordshire is got wholly 
from the Middle Lias. The Northamptonshire ironstone of the Inferior Oolite 
may be traced in the Burton Dassett hills, where it passes into a useless 
sandstone. 
Beds of the Middle Lias stone are seen in the quarries packed with curved 
and interlacing stems something like masses of annelid tubes. They lie upon 
the bedding plane. Other beds of the fine pentangular and smaller ossicles of 
the crinoidiz range between. More rarely the round columnar stems of forms 
like Apiocrinus are found, 
The author infers that the sea floor of the Middle Lias was a tangle of 
crinoid growth, stage above stage. The crinoid sea appears to have spread 
through the Midlands into Yorkshire. Occasionally are phases of invasion or 
dominance of shells of parasitic brachiopoda. Beds of Rhynchonella tetrahedra 
and Jerebratule are interspersed in the 25 feet of the ferro-crinoid rock-bed. 
The quarries and sections in the neighbourhood of Banbury show the several 
phases described. 
In the Nodule Bed at the base of the ironstone series (zone of Spirifer 
oxygona) crinoidal conditions appear in segments and stem casts, mingled with 
large mollusca. Microscopic sections present plates and segments of crinoidiz 
mingled with ferruginous oolitic grains of large size and fox-brown colour. 
The superimposed bed, the Best Rag, has in sections smaller oolitic grains of 
olive-green iron carbonate with ovoid calicular plates of crinoids. 
The Top Rag, a grey-green compact stone, is a tangle of crinoidal and other 
remains more or less broken into and converted into oolitic iron granules. 
The Road Stone, the higher beds, shows its organic structure mainly 
destroyed and converted into the ordinary red oxide. 
