INTRODUCTION, xiii 
to Henley, newer and newer beds are passed over, which lie 
one upon the other and all slanting towards the south-east; 
the beds of the various formations running in irregular lines 
from the south-west to north-east. 
The Lias. The Lower Lias shows itself as a bluish clay in 
the district drained by the Stour, near Ascott, and more 
extensively in the Cherwell valley which is cut down to the 
same formation from the Warwick border to Lower Heyford. 
The Worton brook drains another extensive portion from Great 
Tew to the Cherwell, and the Lower Lias is again present on 
both sides of the Evenlode valley as far south as Charlbury. 
There are but few sections; but one near Banbury shows a 
hard, shelly limestone with numerous fossils; it is locally called 
Banbury Marble; it takes a fair polish and is worked into 
chimney-pieces. 
Marlstone or Middle Lias forms a broad elevated plateau 
situate between the Warwick border on the north and the 
Swere brook. It has outliers of Upper Lias upon it to the west 
and south of Banbury, and a terrace runs along the east side 
of the Cherwell to Rousham, a more or less detached strip 
occurring also on the western side. It also crops out in narrow 
slips on both sides of the Evenlode valley, and portions of it are 
also seen at Great Tew, Little Tew, Heythrop and at Enstone, 
where the Glyme valley has been excavated into the Marlstone. 
The top of the plateau of Marlstone, which is a sandy lime- 
stone more or less coloured by iron oxides, extending 5 or 6 
miles north-west and south of Banbury, is called the Rock bed, 
and at Adderbury is largely worked for iron ore; in 1874 as 
much as 36,000 tons, valued at 72211., having been excavated. 
Ore also exists at Fawler, Swalecliffe, etc. Rhynchonella tetra- 
hedra, R. rimosa, Terebratula resupinata, T. subpunctata, T. 
Edwardsii, etc. are characteristic fossils often found in masses 
called ‘blue jacks’ by the workmen. Thlaspi perfoliatum, 
Genista tinctoria, Polygonatum multiflorum are rare plants 
found on this stratum. 
Upper Lias Clay. This consists of bluish clay and shales 
which once entirely covered the Marlstone, but have been so 
denuded as now to consist only of narrow strips and outliers. 
In some cases portions are let down by faults into the Marlstone 
