[ 47 ° 1 
it may prove of general Ufe, And, left thefe curious 
but thin Partitions of Clay fhould give Way, by 
their Softnefs, for the Particles of Sand to infinuate 
into them, and thereby let the Moifture pafs through, 
thin Crufts of a ferrugineous Subftance are placed 
above and beneath each of thefe clayey Strata, 
and ferve effectually to keep the Clay and Sand 
afunder. 
The Obfemtions you have now read muft be 
underftood to relate to the County of Norfolk only 5 
for I have never had any Opportunity of fearching 
the Bowels of the Earth in other Places ; but the 
general Uniformity of Nature makes me fuppofe the 
Situation and Cncumftances of Pebbles, Sands, &c. 
in other Countries may nojt.be very different. Be- 
lieve me, 
SIR, 
Norwich, March 3, 
1745-tf. Tours, <&rc, 
1 
W. Arderon* 
XII. 
