AND SOME OF ITS EFFECTS. 261 
is 18 inches higher only than the surface upon which the forest 
trees flourished, and therefore Mr. CUNNINGHAM conceived 
that forest trees could flourish as luxuriantly on the present 
surface of the marsh as those of the ancient forest. 
Mr. CUNNINGHAM had entered into some speculations as to 
whether the extensive flat lands on both sides of the estuary 
were encroachments of the land upon the sea, how far those 
encroachments extended, or whether the whole of the flat lands 
were not simultaneously elevated to their present level. These 
questions, although interesting and intimately connected with 
the subject of the submarine forest, were left for future con- 
sideration.” 
That water exists under the Boulder Clay at considerable 
hydraulic pressure can be demonstrated. At Helsby (Cheshire) 
there are several wells in Boulder Clay, which as soon as water 
was struck it rose to the surface, and has in each case continued 
to overflow ever since. 
Mr. Stranan, M.A., F.GS., mentions similar overflowing 
** wells near the Welsh border.’’* 
“Broughton; Well-house Farm.” Above Ordnance datum 
about 22 feet. 
Séarsamd: and 1Oam .\. osu.» as, oes ee 12 feet 
TAME CMAN Fy ob pais nas sary os ns 2 hae 
8 3”. 
‘¢ Water overflowed at the surface ” 
Again at ‘Dodleston; the Rectory Well.” Above Ordnance 
datum about 55 feet. 
Clay apasamd Joe ey Gets Pan 145 feet 
« Water overflows all the year round.” 
Mr. STRAHAN refers also to several others. 
That underground water communicates with the sea is proved 
by Mr CLEMENT REID, F.G.S., who states that ‘‘ at Bridlington 
a boring in the harbour yields a good supply of water. The 
’ quality is excellent, though the level rises and falls with the tide. 
South of the harbour there is another well, connected with a 
stand-pipe. This yields no water at low tide, but about half 
- tide it commences to flow, and continues till the tide again falls 
to the same level. The spring in the harbour is largely used 
for the supply of the town, and is preferred to the natural 
springs.” } 
These phenomena clearly indicate a flow of the underground 
water towards the sea. The fact that peat and forestal remains 
have occurred below low-water mark is a proof that subterranean 
erosion is not limited by tidal influences. We have seen that 
— 
* Memo. Geol. Survey. ‘‘ The Geology of the ageaprereod of Flint, Mold, 
and Ruthin,” pp. 221- 
+ Memo. of the Geol. Survey. ‘‘ The Geology of Holderness, &c.,”? p. 129. 
