THE GEOLOGICAL WORK OF THE AIR. 



355 



THE GEOLOGICAL WORK OF THE AIR. 



BY M. STANISLAS MEUNIEK. 



SOME specimens recently received at the geological laboratory 

 of the National History Museum in Paris suggest a study of 

 the action of the wind in geology and of the importance, long 

 overlooked, of wind deposits. The specimens are lavas from the 

 volcano Mauna Loa, which the wind, lashing them before harden- 

 ing, has reduced to fibers of extraordinary fineness. They might 

 be called bunches of oakum. The mechanism of the formation of 

 these or Pelt's hairs, or bald men's locks, as they are poetically 

 called is similar to that by which similar formations are pro- 

 duced in furnaces when the blast is directed against the melted 

 slags. It has been proposed to employ the product thus prepared 

 as a textile material ; but it is not well adapted to such use, be- 



Fio. 1. PELE'S HAIRS: VOLCANIC LAVAS SPUN BY THE WIND AND RESEMBLING Tow; FROM 

 THE VOLCANO MAUNA LOA, SANDWICH ISLANDS. Natural size. 



cause of frequent abrupt changes in the diameter of the vitreous 

 threads. This peculiarity is shown in Fig. 1, where the little 

 black tears mixed in with the brownish fibrous material are really 

 the knots by which the filaments may at any time be interrupted. 

 If we examine these bald men's locks with a microscope, we shall 

 find the evidences of their wind origin more abundant. Fig. 2 

 represents them magnified fifteen diameters, and Fig. 3 one hun- 

 dred diameters. We see in the former of these figures that, not- 

 withstanding their coarse appearance, the filaments are anything 

 but homogeneous in all their parts. The axial region of each of 



