= 
Rsopt. 15, 1870| 
NATURE 
393 
Looking seaward from the train, the eye can descry 
nothing but range behind range of dunes, the only 
variety being produced by the irregularity of their heights ; 
the only change from the ceaseless monotony of their 
yellow slope, the dark green stripes of dwarf willows 
that serve still more strongly to bring out the sterility o 
the scene. Leaving the train at Ainsdale, or Hightown, 
and examining the Lancashire Sahara more closely, it is 
found to consist of three portions :—a range or series of 
ranges of sand hills, from one to two miles in breadth. 
sloping down to the peat-moss,—a central plain,—and a 
range of sand-hills between the plain and the sea, pro- 
tecting the former from the latter. Their incoherent 
masses would, however, be of little avail, were it not for 
the matted roots of the Sand-reed (Ammophila arun- 
dinacea), locally called “ starr-grass,” and woven by the 
people into mats and other articles, and which grass they 
were unable, until lately, by an old Act of Parliament, to 
cut or destroy, under the most severe penalties. In the 
plain, or rather in the series of small oval plains divided 
from each other by little ridges, running from the sea to 
the land, there is, in the summer, a dense carpet of spongy 
moss, mixed with sedges, and sprinkled with flowers. 
The great quantity of lime constantly set free by the 
dissolving of marine shells in the sand, causes many of 
the plants to be of species generally found on a chalk 
soil. Here occur various plants belonging to the Gentian 
tribe, as the Perfoliate Yellow-wort (Chora perfoliata), the 
Red Centaury (Zrythrea Centaurium, E. pulchella,and £. 
latifolia). Gentiana Amarella,with its purplish-blue flowers, 
will be also found about this time. On the adjoining 
moss-land occurs the rare marsh-gentia, Gentiana Pneu- 
monanthe, with its large blue bell with five green stripes, 
With it grows the Buckbean (Menyanthes trifoliafa). In 
the “slacks” (the local name for the little oval plains in 
the sand-hills), the beautiful Pyro/a medza occurs in great 
abundance, as does also the Grass of Parnassus (Par- 
nassia palustris.) Each of these slacks has a dis- 
tinguishing name, as “ Bull-rush,” “ Long,” “ Mayflower,” 
“Round,” and “ Dale Slacks :” these in winter receive the 
drainage of the sand hills, which, being stopped by the 
carpet of vegetation, forms a series of large standing 
pools of water, in the midst of apparently porous sand. 
To return to the Keuper Marl: it is a series of red, 
green, and grey marls, with occasional seams of freestone, 
much ripple-marked, and beds of shale, generally with 
pseudo-morphous crystals of salt, and often veins of 
fibrous gypsum. Through denudation, the top of it is 
never seen, and it is therefore, with the exception of the 
Drift, the newest formation in the Liverpool district. 
Glacial Drift— Professor E. Hull, F.R.S., proved (in a 
paper read at Manchester, in 1862) that the Glacial 
Drift in the Manchester district was capable of division 
into an Upper and Lower Boulder Clay, divided bya Middle 
Sand and Gravel, which he called the “ Middle Drift.” The 
writer, in a paper on “Glacial Phenomena of Western Lan- 
cashire and Cheshire,” read at the last meeting of the Geo- 
logical Society, attempted to prove that this classification 
holds good, not only in the whole of ‘Western Lancashire, 
but from the River Dee to the flanks of the Cumberland and 
Westmoreland Mountains; and since writing that paper 
he has found that the terrace of Glacial Drift skirting the 
mountains of North Wales, lying between them and the 
sea, is capable of that division, the cliffs of boulder 
clay east of Llandudno (round the Little Orme’s Head) 
being distinctly divided by a M7ddle Sand, containing the 
same species of shells as those occurring in the Lanca- 
shire Middle Drift. 
The Lower Boulder Clay (tne writer endeavoured to 
show, in the paper alluded to above) was formed by an 
ice-sheet, which covered nearly the whole country down 
to a level of about 150 feet to 200 above the present sea- 
level ; this clay he termed the “ High-level Low Boulder 
Clay.” Below a level of 100 feet, the clay appears to have 
been formed by the summer melting of an “ ice-foot,” 
which surrounded the sea-margin—at that level the land, 
through subsidence, standing that amount lower than 
at present. An amelioration of climate then took place 
during which the sands and gravels of the Middle 
Drift, with shells of Celtic type, were deposited round 
the edges of higher, and still higher, successive 
coast-lines, as the land gradually sank, until the sand 
and gravel, at Macclesfield, more than 1,200 feet above 
the present sea-level, was deposited in water of the same 
depth, and containing the same shells, as that in which the 
middle drift of Blackpool, only fifty feet above the 
sea was deposited. The phenomena exhibited by the 
middle drift, of the invariable rise from the sea to the 
land, in aninclined plane—theundulating surface, now far 
below, now up to, but never above, that plane—can only be 
explained by the theory that it was formed as sand- 
banks in shallow water on a_ gradually subsiding - 
tract; and the Uphter Boulder Clay is a marine 
deposit, formed of the detritus brought down by 
glaciers in the valleys of the Cumberland Lake 
district, to the ice-foot, which melting carried its 
spoils over the sea-covered plains. All these divisions are 
more or less well seen in the Liverpool district, especially 
on the Cheshire side of the river, in the neighbourhood of 
Egremont and Eastham. Further south, north of Chester, 
the Middle Drift is particularly well developed. Most of 
the boulder clay in North Cheshire belongs to the upper 
division, the lower clay being absent, having been denuded 
away. Glacial striz were discovered by Mr. Morton 
F.G.S., at Flaybrick Hill, the direction being N. 30° W. 
at an elevation of 120 feet above the sea-level ; and at 
Toxteth Park, the direction being N. 42° W.; also by Mr. 
Hull, F.R.S., at Kirkdale, the direction N. 15° W., 
caused probably by icebergs during the Upper Boulder 
Clay period. 
In the district between Liverpool and Southport a bed 
of sand occurs, forming aline of old sand hills at the inland 
edge of the peat-moss plain, and making a sort of step be- 
tween it and the comparatively high-level (80 to 160 feet) 
boulder-clay plain above. One of these hillocks is called 
Shirdley Hill; I therefore called the sand the “Shirdley 
Hill sand.”* It is about 30 feet thick, and underlies the 
later deposits of the peat plain, but rests itself on a thin 
deposit of what I called the “ Lower Peat.” Above this 
sand, and beneath the great bed of peat (Upper Peat), is a 
bed of grey clay containing freshwater shells, which I 
called the “ Lower Cyclzs clay.” I have observed it from 
the Island of Walney, in North Lancashire, to the coast 
of North Wales, and believe it, as well as the peat above it, 
* “Description of Geol. Surg. Map, 90 S.E.” and “‘ Post-Glacial Deposits 
of Western Lancashire and Cheshire.” read at last meeting of the Geol. Soc. 
