A FOSSIL INSECT FROM THE LOWER PERMIAN OF THE 



GRAND CANYON 



By Frank M. Carpenter 



Of the Biissey InstHiUion of Harvard University 



In the latter part of April, 1926, Mr. C. W. Gilmore, returning 

 to the National Museum with a collection of footprints from tlie 

 Hermit Shale of the Grand Canyon, found among these fossils a 

 large insect wing (Order Protodonata), which had previously been 

 unnoticed. This siDecimen was forv/arded to me by Dr. A. Yv^etmore, 

 to whom I am also indebted for this opportunity of studying the 

 first fossil insect from the Grand Canyon. 



The term "Hermit Shale" was applied by Noble (1922) to the 

 strata previously designated as the "Shale of the Supai Formation," 

 included between the Cocconcino Sandstone (Permian) and the un- 

 conformity topping the Lower Supai Sandstone (Pennsylvania). 

 Typical exposures of the Hermit Shale have been described and fig- 

 ured in the writings of Noble (1914, 1922) and Schuchert (1918), on 

 the Paleozoic of the Grand Canyon, and many of the following com- 

 ments on the geology and paleontology of the deposit have been 

 derived from these sources. The Hermit Shale is a marked contrast 

 to other Paleozoic insect deposits, which are usually characterized 

 by discouragingly small exposures. At the Hermit Basin the shale 

 is from 267 to 317 feet thick; at the Bass Canyon it is 332 feet thick; 

 at the west end of the Kaibab division it is more than 500 feet thick, 

 and may reach 775 feet at the Kaibab Canyon. Noble (1922) de- 

 scribed the beds as consisting of deep brick-red shales and fine- 

 grained friable sandstones. " The beds differ little from one 

 another in composition and consist essentially of sandy mud colored 

 by red ferritic pigment. * * * Many beds exhibit sun cracks 

 and rain prints, and some beds are ripple marked." 



Fossils from the Hermit Shale are few in number, but are suffi- 

 cient to determine the geological position of the deposit. The first 

 specimens were found by Schuchert in 1915. " Just below the sign 

 ' Red Top ' in the lower turn of the Hermit Trail and immediately 

 above the thick upper sandstone of the Lower Supai are seen thin- 

 bedded red shaly sandstones alternating with deep red zones of shale. 

 The surfaces of the glistening and smooth platy sandstones are replete 

 with the fillings of the small prisms of interbedded sun-cracked shales, 

 and are often rain-pitted, and further marked by the feet impres- 



No. 2695.— Proceedings U. S. National Museum. Vol. 71, Art. 23 



48193—27 1 



