4641 



THE GEOLOGIST. 



fine sand, -vritbout pebbles, exhibiting every appearance of having been de* 

 posited by water ; most frequently stratified, but sometimes unstratified. 

 It has generally two well-marked terraces above the waters of the present 

 rivers, as well as some minor terraces. On the top of this is generally 

 found' about three or four feet of silty loam. 



2. Forest sand and gravel. — A deposit of sharp forest sand, parted with 

 layers of gravel of same rocks as No. 1, and having every appearance of a 

 regular deposit by water, distinguishable only from JNo. 1 by its being 



rig. 1. 



found at greater elevations, containing more sand, and being generally 

 more regularly stratified. It sometimes contains thin beds of "till " lying in 

 it, and much drifted coal. 



3. Till. — "Till," a mass of strong brown clay, in which are mingled the 

 same kinds of rocks as those in Nos. 1 and 2, of sizes from six tons in 

 weight to small pebbles, some rounded and partly rounded, and others 

 quite angular, especially coal-measure and magnesian lim.estone rocks, with- 

 out any order of deposition, great and small stones being mixed together 

 indiscriminately, quite impervious to water, and well known as valuable 

 brick clay, and from its being the deposit which yields striated or scored 

 stones. Several beds of fine laminated silt and patches of sand are found 

 in it. 



4. Lower gravel. — A bed of sand or coarse gravel, having the pebbles 

 (consisting of the same kinds of rocks as Nos. 1, 2, and 3) well rounded, 

 sometimes, but not always, occurring under the brick clay, often stratified, 

 and at other times unstratified. It affords good springs of bright water. 



Probably the deposits mentioned above will not always be found in the 

 perfect order there laid down ; no doubt some of them may be wanting at 

 places, especially !N"os. 4 and 2, which have often been removed. 



The kind of gravel found here is somewhat similar to that in the north 

 of France yielding flint implements. Many things have been found in 

 these gravels, but have always been considered of doubtful origin. Some 

 of the old beds of the course of the present river Irwell have been dug 

 out, but little attention has been given to collecting anything from them. 

 It is to be wished that attention were directed to these lowest terrace beds, 

 with a view of ascertaining whether they contain any flint implements or 

 fossil remains, Mr. Earr had stated that he had found a marine shell 

 {Cardmm edule) in the gravel of Stockport. On the top of the gravel is a 

 bed of silt, three or four feet thick, and this seems to have been derived 

 from floods, when the river overflowed its banks and deposited the silt. 

 In the upper terrace there are very often found thin beds of peat, and beds 

 of silt between. 



The great body of gravel, about the level of the waters of the Irwell, has 

 been moved about in the valley as the river has changed its course from 

 time to time. A singular curve of the river occurs below Kersall Moor, 

 which shows that the river may have gone straight across from Douglas 

 mill to the place where the present suspension bridge is erected, a few 

 hundred years ago, for the river on the Salford side is now encroaching 

 on the Broughton side, and the Broughton side is encroaching on that of 



