SCIENCE. 



[N. S. Vol. III. No. 53. 



The lower slopes are occupied by fragments 

 of limestone and sandstone with an ar- 

 rangement showing that they have fallen 

 from the cliff above so as to constitute a 

 talus of the ordinary type, and the central 

 tract is composed of fine material of the 

 same kind. Whatever may have been the 

 original shape of the pit, its present form 

 has resulted from subsequent modification 

 under the action of rain and frost. 



Fig. 3. — Distribution Chart. The inner line is the 

 rim of crater. In the inner shaded area the loose 

 debris has a depth of more than one foot. In the 

 outer shaded area are scattered blocks ; "where the 

 area is bounded by a line its limit was surveyed. 

 The chief district of small iron masses is shown by 

 dots. Large iron masses are indicated by crosses. 

 The distribution of the iron is chiefly on the 

 authority of Mr. F. W. Volz, of Canyon Diablo, 

 A. T. 



ISTo iron has been found within the cra- 

 ter, but a great number of fragments were 

 obtained from the outer slopes where they 

 rested on the mantle of loose blocks. Many 

 others were obtained from the plain within 

 the region of scattered debris, and others, 

 though a smaller number, from the outer 



plain. One large piece was discovered eight 

 miles east of the crater, or almost twice as 

 distant as any fragments of the ejected 

 limestone. Another was long ago discov- 

 ered twenty miles to the southward, but 

 what became of it is not known, and it has 

 not been definitely identified as a member 

 of the same meteoric shower. Most of the 

 masses are small. There have been found 

 more than one thousand, possibly more than 

 two thousand, pieces weighing less than an 

 ounce ; others weigh a few ounces or a few 

 pounds ; fortj' or fifty exceed one hundred 

 pounds, and two exceed one thousand 

 pounds. The total weight of all finds is 

 probably ten tons. At the time of my visit 

 I was told that all had been discovered east 

 of a north and south line passing through 

 the middle of the crater, but this may have 

 been an accident of the method of search, 

 for more recently six large ones have been 

 reported from points west of that line. 



The magnetic survey by Mr. Baker in- 

 cluded the selection and majjping of a 

 system of stations, and the observation at 

 each of the three magnetic elements : the 

 horizontal component of direction, or the 

 compass bearing ; the vertical component 



