Work on Glacial Questions 365 
in the question ever afterwards, and he says “my error has been 
a good lesson to me never to trust in science to the principle of 
exclusion.” : 
Although Darwin had not realised in 1838 that large parts of the 
British Islands had been occupied by great glaciers, he had by no 
means failed while in South America to recognise the importance of 
ice-action. His observations, as recorded in his Journal, on glaciers 
coming down to the sea-level, on the west coast of South America, 
in a latitude corresponding to a much lower one than that of the 
British Islands, profoundly interested geologists; and the same work 
contains many valuable notes on the boulders and unstratified beds in 
South America in which they were included. 
But in 1840 Agassiz read his startling paper on the evidence of 
the former existence of glaciers in the British Islands, and this was 
followed by Buckland’s memoir on the same subject. On April 14, 
1841, Darwin contributed to the Geological Society his important 
paper On the Distribution of Erratic Boulders and the Contem- 
poraneous Unstratified Deposits of South America, a paper full of 
suggestiveness for those studying the glacial deposits of this country. 
It was published in the Transactions in 1842. 
The description of traces of glacial action in North Wales, by 
Buckland, appears to have greatly excited the interest of Darwin. 
With Sedgwick he had, in 1831, worked at the stratigraphy of that 
district, but neither of them had noticed the very interesting surface 
features?, Darwin was able to make a journey to North Wales in 
June, 1842 (alas! it was his last effort in field-geology) and as a result 
he published his most able and convincing paper on the subject in 
the September number of the Philosophical Magazine for 1842. 
Thus the mystery of the bell-stone was at last solved and Darwin, 
writing many years afterwards, said “I felt the keenest delight when 
I first read of the action of icebergs in transporting boulders, and 
I gloried in the progress of Geology®.” To the Geographical Journal 
he had sent in 1839 a note “On a Rock seen on an Iceberg in 
16° 8. Latitude.” For the subject of ice-action, indeed, Darwin 
retained the greatest interest to the end of his life*. 
In 1846, Darwin read two papers to the Geological Society 
On the dust which falls on vessels in the Atlantic, and On the 
Geology of the Falkland Islands; in 1848 he contributed a note 
on the transport of boulders from lower to higher levels; and in 
1862 another note on the thickness of the Pampean formation, as 
shown by recent borings at Buenos Ayres. An account of the 
British Fossil Lepadidae read in 1850, was withdrawn by him. 
1M. L. . pp. 171—93. 20.1.1. p. 58. 
30.L,1.up. 41. 4M. L. 1. pp. 148—71. 
