878 PROCEEDINGS OF THE ACADEMY OF [DeC, 



fragments on the outside of the rim, and to sink a number of shallow 

 shafts through this material, in order to find if possible pieces of the 

 meteor overlaid by and thoroughly admixed with the rock fragments and 

 silica which certainly came from great depths in the adjacent hole. 

 Numbers of these cuts were made before finding the objects of our 

 search, but at last we began to find them and now we have found 

 nearly one hundred pieces of meteoric material, some of them as much 

 as fifty pounds in weight, a number of feet beneath the surface in the 

 silica, overlaid and underlaid in no particular order by the various 

 kinds of rock fragments described above, namely, white sandstone, 

 limestone and red sandstone. In one case that I remember we found 

 a large piece of meteoric oxidized material or "iron shale" about six 

 feet beneath the surface in the silica, directly underneath an angular 

 fragment, several feet in diameter, of red sandstone. On the top of 

 this red sandstone was a piece of limestone, and on top of the limestone 

 was a still larger piece of white sandstone. I merely mention this case 

 as it is interesting to reflect that the white sandstone comes from a 

 depth of at least about 400 feet below the surface, and yet it is found 

 on top of the red sandstone fragment (the surface rock) and the lime- 

 stone fragment which, when the geological order of the rocks is con- 

 sidered, lie above it. However, the most interesting piece of work 

 in this connection which we have done is to be found in one of the shafts 

 on the rim, which shaft is forty-eight feet deep. In this shaft we found 

 vertically one above the other no less than seven quite large specimens 

 of meteoric material or iron shale; the first one being found twelve 

 feet beneath the surface, and the last one being found twenty-seven 

 feet beneath the surface, underneath a large fragment of red sandstone. 

 These pieces were from a pound to probably thirty pounds in weight. 

 On top of the uppermost specimen, and at varying distances between it 

 and the other specimens found in this shaft, there was the usual ad- 

 mixture of silica, white sandstone fragments, limestone and red sand- 

 stone fragments. On no conceivable theory other than the one which 

 we have adopted can the facts above described be explained.^ 



I have used the words "meteoric material" because this material 

 is somewhat unlike any which up to that time had been found on the 

 surface. Such material has, however, since been found on the surface, 



' Since the above was written j\Ir. Tilghman lias informed me that lie has b}' 

 means of a small magnetic separator found distributed through samples of silica, 

 taken from deposits on the slopes of the rim, an appreciable amount of metallic 

 iron in the form of very minute particles and scales which are covered by mag- 

 netic oxide of iron. These of necessity are meteoric in nature. They have been 

 found by him in silica which was taken from several feet beneath the surface. 



