PONDS ON THE SUMMITS OF CHALK HILLS. 197 



wonder, therefore, that they contribute much to pools and 

 streams. 



That trees are great promoters of lakes and rivers, appears 

 from a well-known fact in North America ; for, since the woods 

 and forests have been grubbed and cleared, all bodies of water 

 are much diminished : so that some streams, that were very 

 considerable a century ago, will not now drive a common 

 mill.* Besides, most woodlands, forests, and chases, with us, 

 abound with pools and morasses, no doubt for the reason given 

 above, f 



To a thinking mind, few phenomena are more strange than 

 the state of little ponds on the summits of chalk hills, many 

 of which are never dry in the most trying droughts of summer ; 

 on chalk hills, I say, because in many rocky and gravelly soils, 

 springs usually break out pretty high on the sides of elevated 

 grounds and mountains ; but no person acquainted with chalky 

 districts will allow that they ever saw springs in such a soil 

 but in valleys and bottoms, since the waters of so pervious a 

 stratum as chalk all lie on one dead level, as well-diggers have 

 assured me again and again, J 



Now, we have many such little round ponds in this district ; 

 and one in particular on our sheep-down, three hundred feet 

 above my house ; which, though never above three feet deep 

 in the middle, and not more than thirty feet in diameter, and 



* Vide Kalm's Travels to North America. 



j* For the diminution of some of the lakes and rivers of America, we 

 must seek other causes. About a thousand rivers and streams empty 

 themselves into Lake Superior, sweeping into it earth, primitive boulder 

 stones, and drift timber, which sometimes accumulate so much as to form 

 islands in the estuaries. A lignite formation, indeed, is said to be now in 

 progress, similar to that of Bovey in Devonshire. Within a mile of the 

 share, the water is about seventy fathoms; within eight miles, one 

 hundred and thirty-six fathoms ; and the greatest depth of the lake, 

 farther from the shore, is unknown. Lake Erie, from similar causes, is 

 gradually becoming shallower. Long Point, for example, has, in three 

 years, gained no less than three miles on the water. ED. 



\ In making wells at Modena, in Italy, the workmen dig through 

 several strata of soils, till they come to a very hard kind of earth, much 

 resembling chalk ; here they begin the mason-work, and build a wall, 

 which they carry on at their leisure till they finish it, without being 

 interrupted with one drop of water, and without any apprehension of not 

 finding it when they come to make the experiment. The wall being 

 completed, they bore through the bed of chalk, at the bottom, with a 

 long auger, but take care to ascend from the pit before they draw out the 

 instrument again : which when they have done, the water springs up 

 into the well, and in a little time rises to the brim nay, sometimes over- 

 flows the neighbouring grounds. ED. j 



