466 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vol. 50 



detail. The position they occupy is such as can be accounted for 

 only on the supposition that all the material composing the deposit 

 was in the air at the same moment of time and was deposited 

 "pell mell," wholly without order or reference to gravity, as it fell 

 to the ground. Mr. Barringer speaks of one mass of the iron, found 

 some 6 feet beneath the surface, embedded mainly in the fine white 

 rock-flour ("silica") and directly beneath an angular fragment of 

 red sandstone several feet in diameter, overlying which was a piece 

 of limestone, and over this again one of sandstone. 



The rim of the crater is, as stated, at its highest point some 160 

 feet above the surface of the plain, with a very conspicuous low 

 place (see pi. lxiv) on its northern side. The 5,800-foot contour 

 line (see pi. lxvi) passes along this crest, and it is seen that on 

 the north, and for the most part on the east and south, this is 

 a mere ridge (pi. lxiii, fig. 2) sloping away abruptly on either hand. 

 To the west and southwest the 5,800-foot contour includes two long 

 and comparatively broad areas, near the middle of the southwestern 

 of which are found the highest points on the rim — 5,860 and 5,863 

 feet. The supposed significance of these features of the crest will 

 be noted later. 



A glance at the interior walls of the crater shows at once its 

 nature, if not origin (see pis. lxv and lxix). The details 

 have been given very fully by Messrs. Barringer and Tilghman 

 and less so by Gilbert. They consist of strata, principally of the 

 limestone, but locally of sandstone also, "crushed and shattered to 

 an extraordinary degree" and dipping away (i. e., outward) on all 

 sides at angles of from io° to 8o°, or, in one instance, with an over- 

 turn of at least io° from the vertical. The walls are steep and often 

 overhanging, for hundreds of feet accessible but to birds, and of so 

 loose and friable a character as to make exploration dangerous. A 

 single false step may set tons of loose material slipping and plung- 

 ing down the steep slope. The illustrations utterly fail to convey an 

 idea of their impressive as well as dangerous character. The typical 

 sections here given were made by Mr. Tilghman, to whom I am in- 

 debted for the privilege of utilizing them. It will be noted that at 

 Station 5 (see diagram, figs. 124 and 125) the crater wall is composed, 

 below the surface debris, of (1) a thin bed of red sandstone, and 

 (2) the Aubrey limestone, dipping southwesterly 35 °, the cliff face 

 sloping inward at an average angle of 34 . The underlying white 

 sandstone does not show at this point, being obscured by talus fallen 

 from the cliffs above and the sedimentary beds formed in the bottom 

 of the crater. The "typical east rim" section (Station 18, fig. 125)/ 



