NO. 3 GRAND CANYON FOSSIL FOOTPRINTS GILMORE J 



nated sandstone in the section are massive and relatively compact as con- 

 trasted with the beds that I have designated shale, which are thinly laminated, 

 but the distinction between sandstone and shale is unimportant. All the 

 strata are friable. Many beds exhibit sun-cracks and rain-prints, some are 

 ripple-marked. * * * Everywhere the formation makes a slope which is in 

 strong topographic contrast with the sheer cliff of the overlying Coconino 

 sandstone and with the steplike cliffs and ledges of the underlying Supai. 



The beds containing the tracks in place are horizontal, and, where 

 exposed to the weather, split into thinly laminated sheets ; but as 

 work was continued back into the hillside the layers became more 

 massive. 



In removing these layers it was found that one surface might be 

 covered with tracks and plant remains and the very next one beneath 

 devoid of all fossil evidence. Often a trackway could be clearly 

 traced for a short distance only to become more and more indistinct 

 and finally to entirely disappear, probably due to the varying degrees 

 of softness of the surface at the time the animal passed over it. Some 

 few of the trails have the imprints beautifully distinct but in many 

 the details are destroyed by the inflowing mud after the withdrawal 

 of the foot, which would suggest that they may have been made 

 beneath a slight depth of water. No doubt tracks could be found in 

 the Hermit shale at many other localities were search made for them, 

 but such prospecting as was done where the Yaki Trail crosses the 

 formation failed to disclose any. although plant remains were found 

 in some abundance. 



The recognition of many forms of the same genera as those de- 

 scribed from other Carboniferous areas is of interest, especially 

 those from Joggins and Paraboro, Nova Scotia. The conditions under 

 which these tracks were made in such widely separated localities, 

 seem to have been very similar as evidenced by the many resemblances 

 not only in fauna but in the strtictural and lithologic features of the 

 track-bearing rocks. 



The fauna of the Hermit shale as known at this time consists of 

 the following forms : 



VERTEBRATES 



Batrachichnus delicatula (Lull) 



B. obscunis n. sp. 



Colletfosaurus pcntadactylus n. sp. 



Crusipes sp. 



Dromillopus parvus n. sp. 



Hyloidichnus bifurcatus n. gen., n. sp. 



Hylopus hermitus n. sp. 



Paraharopus coloradcnsis (Lull) 



INVERTEBRATES 



Dragonfly-like insect 



