288 
fossil remains. Agassiz had not as yet broached the great 
conception of the glacial period; the diluvium reigned 
supreme. Year by year more extensive patches of 
fossiliferous clays and gravels were found adjacent 
to Muswell Hill. From Finchley and Whetstone an 
abundance of fossils proper to the chalk and oolite 
formations was obtained, and whole hampers of belem- 
nites were sent off to Prof. Phillips at Oxford for the 
purpose of his monograph on that genus. But the drift 
itself remained an isolated phenomenon. It was left to men 
of the younger generation to attack a problem as worthy 
of solution as the problems of Cambria and Siluria. 
During the last five or six years, the Finchley and 
Muswell Hill drift has excited fresh attention. The 
Great Northern Branch Railway from East End to 
Finchley has exposed some fine sections, and a body of 
earnest field-geologists—the Geologists’ Association—has 
been at hand to take advantage of the opportunities thus 
afforded. In the same period Mr. Wood has published 
his “Sequence of the Glacial Beds,” and the Geological 
Survey a map of the superficial deposits of the district, 
Lying on the hills and plateaux, the North London 
drifts have a scenic interest. They form noticeable 
features in the Middlesex landscapes, as may be seen in 
the accompanying geological map of the district (Fig. 1). 
The valleys and streams around the plateaux delineate 
in an instructive manner the extent of the glacial beds, 
whilst they suggest the action of those meteorological 
NATURE 
forces which have reduced these beds to their present 
limits since their elevation above the sea. 
Royston Down 
(Zerzs ) 
Lhames Valley Brow 
350 SP 507% 
' 
Finchley 
Ficg 2.—Secticn showing the degree of submergence indicated by the upper Glacial Deposits, 
Boulder Clay. c, The Purple Clay without Chalk, 
where these second-hand accumulations of the Lower or | 
Middle Bagshot, disturbed or redeposited, are free from 
the quartzites of the glacial gravels, and exhibit an un- 
mixed Eocene lineage, 
Alter years of untold labour, which offer a noble 
example of private enterprise in the cause of geology, Mr, 
Searles V. Wood, jun., has established the succession of 
the glacial beds of the east of England and the central 
counties, which is here given in abstract :-— 
Post-glacial Beds 
I. UPPER GLACIAL—1. The purple boulder clay of 
Yorkshire without chalk. 2, The purple boulder clay 
with chalk. 3. Zhe Great Chalky Boulder Clay of the 
South of England (e.g. at Finchley and Muswell Hill). 
II, MIDDLE GLACIAL.— The Middle Glacial Sands and | 
Pebbly Gravels of the South-East of England and the | 
Central Counties (e.g., the Finchley and Muswell Hill 
sands and pebbly gravels). 
III. Lower GLACIAL.—The Contorted Drift of Nor- 
folk, the Cromer Till, and the Pebbly Sands of Norfolk 
and Suffolk (Upper Crag). 
A few words further in explication of this sequence will 
show how wide an area of England is concerned in the 
zeae with which the Finchley drifts are thus corre- 
ated, 
+, The Ice Sheet, 4, The Ice-foot, 
The deposit to which the F inchley chalk boulder clay 
belongs stretches in an intermittent way from the lower 
[dug. 7, 1873 
: ar Se 
But unlike the moraines of Snowdonia and other 
mountain districts, these much older lower ground 
accumulations are not, in the view of most English 
glacialists, the immediate deposits of land ice. Contrary 
to the beliefs of the Scotch geologists, who would regard 
them as the equivalents of the Till, they are referred to 
the era of the great submergence of England beneath the 
glacial sea. They are the transported material of the 
submarine terminal moraine. As the ice-foot retired 
before the submerging sea, it left behind it the débris of 
the rocks it had degraded to be transported by bergs and 
rafts over the Middlesex of the future. 
The glacial deposits at Finchley station, although they 
conform to the general character of such beds in the 
south-western counties, have certain features which may 
prove to be more developed here than elsewhere, and may, 
at some future time, help to connect these deposits with 
their more local sources of supply. The preponderance 
of the characteristic Oxford clay fossil Gryptea dilatata is 
remarkable, and whilst the chalk and the Oxford clay are 
the most largely represented, the formations of which the 
fewest traces are found are the gault and the London 
clay. Foreign blocks, transported by ice, are generally 
absent from the district. Blocks of Sarsen sandstone are 
not uncommon, but it is worthy of notice that they are 
only found in the drift. 
The vast sources of supply for the flint pebbles which 
abound in the glacial gravels of the district are still repre- 
sented in the small and local remainders which cap the 
high ground at Totteridge, and are found at Barnet, 
Lorkshire Moorlands 
Basi 
7500 Zo 1400 fe 
Westmoreland 
fells 
References—-a, The Middle Glacial. 
6, The Chalky 
2, Floating Ice. 
Thames Valley to Central Lincolnshire, 
Eastern Counties of Norfolk and Suffolk to East Stafford- 
shire, The Finchley sands and gravels extend (mostly 
covered by the boulder clay) over nearly all the three 
large counties of Norfolk, Suffolk, and Essex, and are 
present in Herts, Bucks, and Leicester. So there is no 
insignificant number of geologists, away from the region 
of the old glaciers, who may study in their own locality 
the memorials of the great glacial period in England. 
Inasmuch as the maps which Nature has laid down 
in the ground beneath us are historical as well as physical, 
this sequence introduces us to a series of consecutive 
events in the earlier history of the great Glacial Period. 
In the lower glacial the age of Ice begins, In the next 
deposit we notice a pause in the Arctic conditions which 
had prevailed. The formation of that characteristically 
glacial deposit, the boulder clay, was arrested, and the 
sands and gravels (middle glacial), of milder waters, took 
its place. Then the Arctic conditions returned, and 
brought in the chalky boulder clay, At length the higher 
rocks were brought within the reach of the sea, until the 
Yorkshire Wolds were submerged, and eventually the 
Westmoreland fells yielded their dééris to be spread over 
the sea-bottom (Fig 2). That the glacial period should 
have left its memorials so far south in our island as the 
valley of the Thames, was a matter of incredulity among 
many geologists, even so recently as ten years since, when 
Sir Charles Lyell had compelled attention to the Mus- 
well Hill drift in the “ Antiquity) of _Man?’.. That the 
and from the 
