144 
A. E. SALTER-HERTS GRAYELS. 
The Grayels connecter with the Anti-rip (obseqhent) Streams 
PLOWING NORTHWARB EROM THE ESCARPMENT. 
Several small streams occur north of the escarpment, hut the 
Hiz is the only one we need consider. 
There is much gravel around Hitchin, consisting mainly of flint 
and such non-local material as has found its way down from the 
higher parts of the Chalk slope near the escarpment.* Pits occur 
near the TJnion, and at Highbury, Hitchin. At Clay Push Hill 
near A shwell is a deposit of similar derivation. As before mentioned, 
the gravel-deposit at 500 ft. O.D. on Gravel Hill is close to the 
edge of the escarpment, and will, as denudation proceeds, descend 
to lower levels, and help in the formation of more recent deposits. 
In this way the non-local material of this district has been derived 
in former times. The late age of the gravels near Hitchin is shown 
also by the presence of Palaeolithic implements, etc., as described 
by Mr. Clement Reid, E.R.S.f 
Conclusions. 
It will he seen from the foregoing remarks that the origin of 
the gravel-beds of Hertfordshire can be explained on a hypothesis 
giving great prominence to subaerial and fluviatile agencies, hut 
that it is necessary to assume that the synclinal basin of the 
Thames Yalley has undergone modification or accentuation. The 
disposition of the gravels shows that this was as a rule a slow 
process, although there appears to he some evidence for supposing 
that the initiation of the present system of drainage may have been 
brought about more rapidly. The most potent factor, as seen by 
the heights of the earlier gravel-beds, has, however, been the slow 
hut ceaseless action of the ordinary agents of denudation acting 
through a long period of time.J 
* W. Hill, “ Excursion to Hitchin,” ‘ Proc. Geol. Assoc.,’ vol. xiv, p. 415. 
f Cf. “ The Palaeolithic Deposits at Hitchin and their relation to the Glacial 
Epoch,” ‘Geol. Mag.,’ 1897, p. 228; ‘Proc. Roy. Soc., 5 vol. xli, p. 40; 
‘ Trans. Herts Nat. Hist. Soc.,’ Yol. X, p. 14. 
I There are numerous references to Hertfordshire gravels in which Palaeolithic 
implements occur in ‘Ancient Stone Implements’ by Sir John Evans. See also 
his Anniversary Address (1895) on “ The Stone Age in Hertfordshire,” in ‘Trans. 
Herts Nat. Hist. Soc.,’ Yol. YIII, pp. 169-187.—Ed. 
