202 CARNEGIE INSTITUTION OF WASHINGTON. 



fragments. These various evidences of fragmentation imply a 

 previous history affected by successive conditions of accretion and 

 fracturing. 



The pressure of slickensided surfaces impHes a parent body which 

 was subjected to varying stresses, resulting first in fracture and 

 afterward in the rubbing of the fissure walls upon one another. 

 The existence of veins also implies fracture attended by subsequent 

 filling. 



The general prevalence, but partial absence, of crystallization and 

 the kinds of crystallization imply varied thermal conditions in the 

 parent body. The amorphous condition implies the absence of fusion 

 and of the conditions of cr^-stallization. The glassy structure equally 

 implies a molten state followed by quick cooling, while the various 

 grades of crystallization imply high temperatures variously sustained. 

 The extremely large crystals suggest protracted high temperature, 

 with conditions favorable for a highly systematic rearrangement of 

 the material. At the same time the frequent cases in which the 

 metallic iron is scattered through the silicate material seem to imply 

 the absence of a completely fluid state, for in that case segregation 

 of the heavy metallic material toward the center of the bod}' should 

 take place. The same is perhaps indicated by the frequent presence 

 of nodules of sulphides and phosphides within the masses of iron. 

 These conditions seem best explained by a prolonged high tempera- 

 ture acting on a mass of mixed material and furnishing conditions 

 suitable for slow aggregation and crystalline rearrangement without 

 complete fluidity being reached. 



It is hard to believe that these coarse crystallizations could have 

 been formed in small masses of matter projected into space in the 

 molten condition, and the view that meteorites are formed directly 

 from lavas shot into space by volcanic or other explosive action, as 

 from a sun, a planet, or the moon, is unsatisfactor}- in this particular. 

 Equally adverse to this view is the extraordinary fact that certain 

 classes of meteorites are formed chiefly of hydrocarbons which are 

 volatile at moderately high temperatures and are readily combus- 

 tible. These hydrocarbons seem prohibitive of high temperatures 

 at all stages of their history, and it is a marvel that they should 

 survive the transit through the atmosphere ; but this is probably due 

 to the fact that they were excessively cold when they entered it and 

 during the brief time of their transit were only superficially con- 

 sumed, while their interiors remained cold, as the interiors of me- 

 teorites are not infrequently found to be immediately after their fall. 



