228 Professor Agassiz on the Glacial Theory, 



them to disappear. This arrangement is very well seen in 

 the environs of Neuchatel. 



The state of matters is by no means the same in Britain, 

 and more particularly in Scotland. There the erratic blocks 

 of all dimensions are, in certain circumstances, rounded, per- 

 fectly smooth and polished, and even scratched with rectilinear 

 striae, like the polished solid rocks — a feature only observed 

 in the smaller pebbles in Switzerland. It is not to be under- 

 stood that there are no large angular blocks in England and 

 in Scotland ; but there is this distinction to be made, that 

 these blocks are generally not far distant from their natural 

 position in situ, or that they are in small number compared 

 with those which have evidently been acted on by a prolonged 

 mechanical operation. But this is not all ; far from being 

 found lying at the surface of the ground, the large blocks are 

 for the most part heaped up in a confused manner along with 

 the smaller ones of all degrees of size, from the dimension of 

 the smallest pebbles to the colossal volume of the largest er- 

 ratic blocks, in a deposit of clay unequally distributed over 

 all the low portions of the country. This deposit of clay, 

 which is of very unequal thickness, and exhibits no trace of 

 stratification, is what is termed till in Scotland. There is no 

 locality in which I have been able to study the till more com- 

 pletely than at Glasgow, where the numerous works carried 

 on in 1840 for the embellishment of the town had exposed it 

 at many points ; but everywhere it presents the same charac-. 

 ters ; the rounded, polished, and scratched blocks of very va- 

 rious dimensions, are every where indiscriminately mixed to^ 

 ge'ther in a marly or clayey paste. It is evident that it was 

 with this mass, and in this mass, that the rounded and polish^ 

 ed blocks have been transported during the whole journey 

 M hich they have performed together, while the angular blocks 

 have certainly not been rubbed in this manner. Mr T. Ed- 

 ington has, to the advantage of geologists, brought together, 

 in his park at Glasgow, a magnificent collection of these po- 

 lished and scratched blocks from the neighbourhood of the 

 town. 



Differences of this description in the facts observed at dif-. 

 ferent localities, are an additional difficulty for all those who 



