228 ANNUAL REPORT SMITHSONIAN INSTITUTION, 195 4 



like, as the rough edges are smoothened in flight. Additional sculptur- 

 ing effects, such as smooth lines and grooves, result from the removal 

 of glass in an uneven manner, presumably in part by the particular 

 aerodynamical forces brought into play with the object traveling 

 at such a high velocity, assisted by a more rapid melting of the 

 softer striae within the glass, but later modified greatly by weather- 

 ing and chemical reactions and resulting in the removal of quantities 

 of glass where the more solvent material or other inhomogeneities oc- 

 curred. Plates 1, figure 2, and 2, figure 1, illustrate beautifully the 

 character of some of these surface features. Some of them are worm- 

 like grooves and navels, often completely interlacing the surface of 

 the specimen. This feature is more pronounced in some of the billi- 

 tonites (pi. 1, fig. 2) which have probably been buried in moist soil 

 for a long time. When examined under low-power magnification 

 (about 10) numerous fine surface lines and figures, probably corre- 

 sponding with the internal striae (see pis. 3 and 4) of the specimen, 

 may be observed both on the outer surface and within the pittings. 



It has been noted that the tektite glasses do not contain inclusions 

 of other materials such as are found in many ordinary types of mete- 

 orites. Suppose inclusions did occur within the glass. Such material, 

 if of fine structure, would have been completely melted and have be- 

 come a part of the glass body. If not of fine structure, it would prob- 

 ably have had a temperature coefficient of expansion so much differ- 

 ent from that of the glass that when the slab of glass containing the 

 foreign material hit the atmosphere rupture would occur along the 

 dividing surfaces. Furthermore, greater shattering would probably 

 result so that the smaller pieces of material would probably either be 

 completely disintegrated in flight or else land with all surfaces origi- 

 nally containing the two kinds of material being completely obliterated. 

 Glass meteorites, composed of softer glasses, which would have a lower 

 content of silica and higher amounts of potassium or some of the other 

 oxides having high coefficients of thermal expansion, would be expected 

 to shatter into much smaller fragments and then to be completely fused, 

 possibly vaporized, before landing. Hence, recovery of any soft, low- 

 melting type tektite glasses would at best be rather improbable. 



It has been suggested by Nininger (1952) that the tektites are glassy 

 material splashed from the moon during the course of a meteoric col- 

 lision ( and the resulting explosion ) . The splashing of the moon mate- 

 rial cannot be denied, and some of it no doubt eventually reaches the 

 earth, but it is thought that its composition, while glassy (Stair and 

 Johnston, 1953), could not possibly correspond to the near-perfect 

 glass of tektites because of the lower temperatures under which the 

 moon was formed. Nor could glass of this type result in a flash 

 reaction for the reasons noted previously. 



