2qo Field Columbian Museum — Geology, Vol. I. 



trusion of the more resistant grains. In many places, especially in the 

 vicinity of the pits, minute thread-like markings appear over the sur- 

 face, sometimes in parallel and concentric series, but more commonly 

 in arborescent forms which are often quite elaborate. These series or 

 systems of markings do not appear to run in any common direc- 

 tion, but are differently oriented wherever found. I have noted no 

 system more than one inch (2.5 cm.) in length, but several of about 

 this extent. They resemble closely the lines of flow such as have 

 been noted on the crust of the Stannern and other meteorites, and 

 doubtless are of this nature, being formed by a minute portion of the 

 substance of the meteorite becoming momentarily fused and flowing 

 in a diversified path until cooled. Their course in some cases seems 

 to mark the swirling of the same air currents which formed the pits. 

 More extensive and larger ridges are to be observed over some por- 

 tions of the crust. Three nearly parallel appear on the portion of the 

 Kiickseite just mentioned. Each is continuous for a length of from 3 

 to 5 inches. These do not appear to be of the nature of the lines of 

 flow above mentioned, but more nearly resemble the veins which stand 

 out on some meteorites and probably mark a line of more highly re- 

 sistant constituents. Sections cut at right angles to the crust and 

 examined with the microscope exhibit little if any alteration on the 

 crust surface. The mineral outlines seem to be continued sharply up 

 to the edge, and except for a certain smoothness of contour a crust 

 surface could not be distinguished microscopically from the surface of 

 an interior portion. Occasionally a metallic grain protrudes from the 

 general outline, but so far as the contour as a whole is concerned it 

 appears to be the result of erosion rather than of fusion. 



The weathering which the mass has undergone since its advent 

 upon the earth has affected it considerably. Even the larger frag- 

 ments when broken open will be found to be deeply invaded by rust 

 which has penetrated along cracks in every direction. Doubtless 

 the great number of small fragments into which the stone was found 

 to be broken when first discovered was due to this process of sepa- 

 ration through weathering rather than to shattering caused by the blow 

 of the mass upon the earth. The weathering has affected chiefly the 

 metallic constituents of the stone, causing their oxidation, and 

 this rust has penetrated and stained the meteorite deeply. The color 

 of the weathered, surfaces has thus been changed from the dark green 

 of the unaltered rock to various shades of brown, a characteristic 

 color being a light yellowish brown, almost white, spotted with dark 

 or rust brown. 



The depth to which this discoloration has extended, except where 



