TRANSACTIONS OF SECTION C. 475 
vw 
been the result of flood action tearing up a deposit cracked by drying and 
transporting the fragments for some distance. 
There is strong evidence to support the view that two at least of these 
limestones were formed over a large area; the Index has rarely been removed 
completely by this process; the one next above often has. How far the less 
persistent beds have been locally removed by subsequent erosion is at present 
an open question. 
This mode of origin of the more impure, possibly of all the limestones, is 
supported by the character of the sandstones. These at their base often con- 
tain abundant pellets of marl, which from their form appear to have been sun- 
dried and so rendered sufficiently coherent to be capable of transportation for 
short distances without losing their cuboidal form. The phenomena suggest 
formation in shallow water, during a dry epoch, subject to sudden or periodical 
floods. 
4. On the Stream-Courses of the Black-Country Plateau. 
By Henry Kay, F.G.S. - 
The Black-Country plateau is roughly outlined by the 400-feet contour line 
between Stafford, Worcester, Stratford, and Burton, and is identical with the 
anticline of the South Staffordshire coalfield, plus the north-western parts of 
Cannock Chase and the Warley-Barr area eastward. On its eastern and western 
sides are synclinal valleys opening to the Trent and Severn. 
It is surrounded by a marginal hill barrier, and has large hill masses at 
Cannock Chase and the Clent region; while it is crossed by hill ranges from 
Bushbury to Barr Beacon, from Wolverhampton to the Lickeys, and from 
Quinton to Birmingham. The surface is thus divided into four interior basins, 
forming separate drainage areas. Save for the exits from these basins, the 
margin is broken in two places only. The chief physical feature is the possession 
of the crucial portion of the Midland watershed, which runs across the plateau 
from Wolverhampton to the Lickeys, and thence eastward along the southern 
margin. 
Arterial drainage is supplied by the Trent and Severn, the former draining 
five-sixths of the plateau, and the latter receiving only the southward marginal 
drainage and that of the Stour basin. 
The eastern syncline is occupied by the River Blythe-Tame flowing north. 
The watershed at the southern end of this valley has retreated northwards for 
four miles in post-glacial time. 
The western syncline was formerly drained towards the Dee, and the head- 
waters of the Severn were originally around Kidderminster, the Clent range 
being united with the Enville hills further west. The principal outlet towards 
the Dee was by the Church Eaton Water, and the outlet into the Trent below 
Stafford not then in existence. This syncline is now drained northward by the 
Penk into the Sow and Tame, and southward by the Smestow-Stour into the 
Severn. Stream piracy is manifest near Wolverhampton. 
Marginal streams are characterised by excessive activity, especially south- 
ward, notable examples being the Arrow and the Alne. The Arrow, however, 
represents the captured headwaters of an ancient river flowing through the 
Moreton Gap into the Evenlode, the pirate stream being the Warwickshire Avon, 
a strike river originally confined to the country west of Evesham. The water- 
shed then ran southward from the Lickeys to the Cotswolds, keing now repre- 
sented by a long, narrow promontory reaching into Evesham and by Bredon Hill 
southward. Internal drainage is confined to the four basins. The Cannock 
Basin has now no trunk stream, its waters uniting near the exit below Cannock 
to form the Saredon Brook. Glacial modification is much in evidence, the south- 
eastern portion having formed a lakelet with gorge-like overflow through Walsall. 
The margin of this basin has twice been broached by marginal streams. The 
Tame Basin is triangular in shape, and formed by the union of two basins reach- 
ing back to pre-Triassic ages, a large buried stream-course existing at Moxley, 
whilst a very great valley is traceable upwards through Smethwick, Oldbury, 
and Blackheath. At this point two buried stream-courses are found, each filled 
with material transported from the Clent Hills. The inference is that this 
