MANCHESTER GEOLOGICAL SOCIETY. 
113 
nesses, and often lying within the last-named deposits. Sth, 
Deposits of gravel and sand^ both stratified and nnstratified, 
found in the beds of valleys and low lands adjoining river and 
brook courses. In addition to the above named descriptions of 
drift, a bed of rich loam is frequently found covering the deposits 
in the valleys. This has evidently been brought down by the 
present rivers. The land in the valley of the Irwell, near 
Agecroft Bridge, will illustrate the nature of the soil I allude to, 
and may be justly termed alluvion. The drift does not always 
occur in the order above described, nor are all the members of it 
constantly present, as several examples hereinafter mentioned 
will show ; but the above classification will enable me to give a 
clearer view of the general phenomena in the low and gently 
rising ground. In the vicinity of Manchester, from Pendleton, 
across the valley of the Irwell, to Kersal Moor, all the series may 
be observed in the order above mentioned. All persons acquaint- 
ed with the counties of Lancaster and Chester are well aware, 
that the surface of the whole of the low portions of the country 
is covered with a thick deposit of drift, sometimes a strong clay, 
mixed more or less with pebbles, known by the name of marl by 
the farmers, brick-clay in the neighbourhood of the towns, and 
as " tiir^ by the geologists, or fine forest sands or gravels, forming 
the light soils. Deposits of peat cover both these, but most 
generally the latter ; and where peat is found upon the former, 
the bed of sand or gravel is not very thick, and a bed of strong 
clay nearly underlies it. These superficial deposits so envelope 
the country, that a view of the underlying rocks, whether new 
red sand-stone or coal measures, is rarely to be had, except in 
the great lines of drainage, or in artificial sections. The same 
may be said of the greater part of the profitable portions of the 
coal fields of St. Helenas, Wigan, Worsley, Bolton, Eadclifi*e, 
Bury, Heywood, Middleton, Oldham, Ashton, Dukinfield, Hyde, 
Houghton, Bradbury, and Poynton. The lower coal field occu- 
pying the higher part of the country is most free from it ; but 
