27 
instead of being of the same colour as the gravels in which they are found, are 
of a different colour altogether, showing that they have previously been 
deposited in certain beds where they have obtained the colours they exhibit, 
and that they have afterwards been transported to, and deposited in the beds 
in which we now find them. I have here a few specimens of the implements 
of the Neolithic (or Later Stone) period, in which age the hatchets were 
frequently ground so as to form a cutting edge ; but in the case of imple- 
ments from the gravel, we have not discovered any which bear signs of 
grinding upon them.* Iam quite prepared to accept what Mr. Michell has 
this age and the deposits of the sea, or the older glacial beds ; and to dis- 
tinguish fossils of the older post-pliocene, which must often/ m the process 
of sorting by water, have got mixed with those of the newer. After animal 
and vegetable life had overspread the new land, palaeolithic man was intro- 
duced, & on the Eastern Continent, and was contemporary with both existing 
and extinct species. Dr. Dawson adds, “ in thus writing, I assume the accu- 
racy of the inferences from the occurrence of worked stones with the bones 
of post-glacial animals. After this there seems to have had a rapid subsidence 
and re-elevation of the earth, the geological deluge, which separates the_ post- 
glacial from the modern, and the earlier from the later prehistoric period ot 
the archaeologists ; and it is f not impossible that this constituted, the deluge 
of the Bible. As to the time required for the post-glacial period it has been 
much exaggerated, the calculations of long time based on the gravels of the 
Somme, the cavern deposits, the delta of the Tiniere, and the peat bogs of 
France (the peat bog of Abbeville is a forest peat, and the stems in it show 
that it grew at the rate of three feet in a century ; it is 26 feet thick), 
and Denmark, on certain cave deposits, have all been proved to be at fault, 
and probably none of these reach further back than 6,000 or 7,000 years, 
which, according to Dr. Andrews ( Transactions of the Chicago. Academy, 1871), 
have elapsed since the close of the boulder-clay deposits in America. In 
1865 I had an opportunity of examining the now celebrated gravels of St. 
Acheul, on the Somme, by some supposed to go back to a very ancient 
period. With the papers of Prestwich and other able observers in my hand, 
I could conclude merely that the undisturbed gravels were older than the 
Eoman period, but how much older only detailed topographical surveys 
could prove ; and that taking into account the probabilities of a different 
level of the land, a wooded condition of the country, a greater rainfall, and 
a glacial filling in of the Somme Valley with clay and stones, subsequently 
cut out by running water, the gravels could scarcely be older . than 
the Abbeville peat.’' Dr. Dawson, in like manner, fails to perceive,— 
and believes American geologists will agree with him, any evidence of 
great antiquity in the caves of England or Belgium, the kitchen middens of 
Denmark, the rock shelters of France, or the lake habitations of Switzerland. 
He also speaks of Dr. Andrews’ observations on the raised beaches of 
Lake Michigan, observations which have been much more precise than any 
made in Europe, enabling him to calculate that North America rose out of 
the waters of the glacial period between 5,500 and 7,500 years ago, ana 
thus fixing the duration of the human period in America ; there are other 
lines of evidence which would reduce the residence of man to a much shorter 
period ; longer periods have been deduced from the. deposits at the . delta 
of the Mississippi, but Hilgard has found tliem to be in great part marine. 
* Sir John Lubbock has suggested the terms Palaeolithic and Neolithic 
for the two main divisions of the Stone age. Implements of the Palaeolithic 
