MERRILL] METEOR CRATER OF CANYON DIABLO, ARIZONA 465 



tion derived from what is now the crater interior. Masses of sand- 

 stone and limestone, from the finest rock-flour to those weighing 

 hundreds and even thousands of tons, are scattered about in the 

 wildest profusion (see pis. lxii and lxiii). The larger blocks are of 

 limestone, but this, as noted by Gilbert, is due to the rapid disintegra- 

 tion of the sandstone under atmospheric influences. They are most 

 abundant on the east and west slopes, and lie on or near the crest 

 of the rim, from which the debris spreads out in gradually diminish- 

 ing quantities for distances varying from one-fourth of a mile to 

 nearly a mile, or in some instances, according to Gilbert, to a dis- 

 tance of y/2 miles. The block shown in figure 12 of Mr. Gilbert's 

 paper is described as 10 feet in height and as lying some half a 

 mile outside of the crater rim. Perhaps the most significant feature 

 of the ejectamenta is the occurrence of enormous masses of the sand- 

 stone which have undergone a partial metamorphism through crush- 

 ing and heat in a manner to be described when speaking of the 

 materials found inside of the crater. It is sufficient to state here 

 that this material must have come from a depth of at least 300 

 feet below the original surface. In this connection may be mentioned 

 also the rock-flour ("silica" of Mr. Barringer's paper), which, while 

 occurring on nearly all sides of the crater, is particularly conspicu- 

 ous on the southern slope, where it has been cut through by a dry 

 "wash," and is exposed for a distance of hundreds of feet to a depth 

 in some cases of upward of 10 feet (see pi. lxvii, fig. 1). This is of 

 a chalky white color, has a sharp, gritty feeling when rubbed between 

 the thumb and fingers, and, as shown by the microscope, is composed 

 of the shattered grains of the gray sandstone. It will also be de- 

 scribed in detail later. 



At various points along the lower margin of the crater, and par- 

 ticularly toward the north, are many low, rounded, moraine-like 

 deposits composed of the same material as the rim, but for the most 

 part in a comparatively fine state of disaggregation (see pi. i.xviii, 

 fig. 1). In pits and trenches, sunk in these, are found fragments of 

 all the rocks indigenous to the crater, and, what is of still greater 

 interest, many of the shale-ball irons described elsewhere 1 and 

 first brought to notice by Mr. Barringer. The occurrence of these 

 is fully described by Mr. Barringer, and subsequent excavations made 

 in the writer's presence corroborated his description in every 



1 See also Contributions to the Study of the Canyon Diablo Meteorites by 

 George P. Merrill and Wirt Tassin, Smith. Misc. Collections (Quarterly 

 Issue), vol. 50, p. 203. September, 1907. 



