312 "Report of the 'Researches of M. Agassiz. 



enclosed a regular bed of gravel nearly half an inch thick, and 

 which penetrated into a depth of more than two feet. Our 

 attention being excited by this occurrence, we examined the 

 glacier with this object, and it was not long before we disco- 

 vered gravel, and the minute debris of rocks in many other 

 bands. At a later period, when we had learned to distinguish 

 between the strata of the glacier and the blue bands, we regu- 

 larly found that the greater number of the projections of the 

 strata were accompanied with a slight bed of gravel ; and, as 

 it always happens, these traces of gravel become, in their turn, 

 a distinctive character of the strata. 



Whilst boring the gallery of infiltration, we likewise re- 

 marked traces of gravel in many places at the depth of eighteen 

 feet. We even discovered in the roof of the gallery a com- 

 mon fly in perfect preservation, with its wings and legs entire, 

 and at the distance of a few inches many fragments of differ- 

 ent grasses equally well preserved. When we had once ac- 

 quired the certainty that all parts of the glacier enclosed fo- 

 reign bodies in greater or less quantity, wishing to take an 

 approximate measure of this quantity, M. Agassiz caused the 

 splinters of ice to be collected which the piercer detached 

 from its point, which their lesser specific gravity brought to 

 the surface from a depth of about 20 feet. These splinters 

 were all of an ice apparently pure and perfectly transparent, 

 especially where the air-bubbles did not superabound. The 

 quantity of ice thus collected yielded 27 quarts (litres) of wa- 

 ter. This water deposited, at the bottom of the containing 

 vessel, which had been thoroughly cleaned, a layer of very fine 

 siliceous sand, which weighed 64 grammes, so that each quart 

 of water did not contain less than 2^ grammes of foreign mat- 

 ters, or about 50 grains. 



What was the origin of this sand X A question this which 

 may the more naturally be put, after it has been so long held 

 and taught that the glacier ice does not contain, and could 

 not contain, any foreign body. To explain the presence of 

 this sand in the interior of a glacier, and at all depths, it is 

 necessary to remember that each bed of snow which falls 

 during the winter in the elevated regions remains uncovered 

 during the ensuing summer, — that during this season the wind 



