[ lOS ] 
IV. An Account of some recent Researches near Cairo, undertaken with the view of 
throwing light upon the Geological History of the Alluvial Land of Egypt . — 
Instituted hy Leonard Horner, Esq., F.R.SS. L. ^ E., F.G.S. 
PART I. 
Received January 25th, — Read February 8th and 15th, 1855. 
Contents : — 
Introduction, page 
Physical Geography and Geological Structure of Egypt 109 
The Inundations of the Nile 114 
The solid matter conveyed by the Nile to form its sedimentary deposits 117 
The Recent Researches 119 
The Excavations at Heliopolis 123 
Descriptions and Analyses of the Soils 124 
Descriptions of the several pits sunk 131 
Synopsis of the soils sunk through in the excavations . . 137 
INTRODUCTION. 
The progress of geology has demonstrated, that the portion of the crust of the 
globe which is accessible to us, has been formed by a series of successive operations, 
and that each member of the series of great changes must have required a period of 
vast duration for its development. We learn from the astronomer that the mean 
distance from our earth to the sun is ninety-five millions of miles, and that the 
distance which separates us from the 61st star of the Swan is 412,000 times ninety- 
five millions. Although he thus describes an extent of distance of which it is scarcely 
possible for us to form a just conception, still he expresses himself in definite terms. 
Not so the geologist: while the astronomer with his telescope penetrates into the 
remotest regions of Space, and in the known velocity of light has a scale by which he 
can estimate the vast distance, the geologist looks into an unfathomable abyss of 
Time ; for no power of sounding its depth has yet been discovered. If he attempts 
to assign a definite term, in time, for the period of the formation of any particular 
series of strata, even among those that belong to the most recent of the tertiary de- 
posits, he has hitherto sought in vain for any reliable scale of measurement ; and he 
speaks of thousands, or millions, or myriads of years or ages, just as imagination 
leads him to give a form to his ideas of vast immeasurable antiquity. 
It is scarcely within the range of possibility that the absolute age of the earth’s 
crust, reckoned in years backward from some historical epoch, will ever be disco- 
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