200 Sir H. H. Howorth — Surface Geology of N. Europe. 



in so far as they consist of boulders, have in every case where they 

 Lave travelled, and we can trace the mother rock in situ, moved from 

 north to south, and were never in the reverse direction. 



One of their most important features, and one which has been 

 a great deal too little noticed in the vai'ious theories which have been 

 forthcoming to explain them, is the fact that they traverse the 

 country quite iri'espective of its contour, going uphill and downhill, 

 and athwart the natural drainage. On this point I will quote the 

 language of a first-rate authority, Erdmann. After saying that they 

 sometimes run along the valleys, sometimes on the mountain flanks, 

 and sometimes on the plateaux, he adds (in italics) the words : "C'est 

 ainsi qu'elles continuent leur cours lointain, franchissant lea plateaux, 

 les vallees, et les plaines, et ne semblant en aucune maniere s'inquieter 

 des reliefs divers actuels du pays." ("Expose," etc., p. 41.) This 

 is a conclusion drawn from the Swedish asar. The Finnish ones are 

 quite as remarkable, traversing lakes and watersheds without any 

 hesitation. 



As I have said, a large portion of the asar consist of masses of 

 rounded stones of various sizes up to 2 feet in diameter. These 

 rounded stones are not mixed with angular erratics. The latter, 

 when they occur, do so in the upper and more sandy and loamy 

 layers, or scattered over the asar's backs, nor, so far as I could observe, 

 do they contain stones of exceptional size. These, again, chiefly 

 occur in the sandy beds or on the backs of the asar. Their contents 

 are not sorted according to their size, but the stones generally lie 

 with their longer axes parallel to the direction of the as in which 

 they are found. The beds of sand and the sandy asar are in nearly 

 all cases more or less stratified. They are frequently false-bedded, 

 and the beds which show the false-bedding have their lines very 

 pronounced, the angular wedges of sand and the lenticular masses 

 being on a large scale and very marked. The uppermost layers of 

 the asar often consist of stiff blue clay or of finely sifted and 

 laminated brickearths, containing in places numbers of diatoms 

 and marine shells, but never, so far as I know, fresh-water debris 

 or land molluscs. These beds of brickearth and clay occur only 

 at the top of the asai', where they are often intercalated with 

 sand beds very irregularly disposed, just as they are in the beds of 

 contorted drift in the Cromer cliffs, and they are generally continuous 

 with the mantle of similar loam that covers the intervening country. 

 I cannot follow Erdmann and Geikie in separating these superficial 

 layers in the asar from the beds below. So far as I can judge (and 

 here, again, the present condition of the cutting at Upsala is very 

 pi-egnant with meaning), they pass continuously down into them, 

 and are merely later phases of one deposit, just like the similar 

 phases we see in the drift beds of East Anglia. Lyell, Murchison, 

 and others, who examined the asar with care and skill, and whose 

 judgment was in this case un warped by a priori theories of the 

 origin of the asar, treated the superficial beds containing marine 

 shells as belonging to the same period as the lower beds, which are 

 barren and consist largely of boulders. 



