MEMOBIAL 0¥ C. W. HAYES 97 



nished the final key tO' the complex structure of the Appalachians. His 

 exposition was so clear and his facts were so convincing that the inter- 

 pretation almost at once found general acceptance. The broad thrust- 

 fault type of Appalachian structure so soon became axiomatic that the 

 fact of its being Hayes's discovery was soon lost sight of in geologic 

 literature. The principle developed by Hayes of overthrust faults along 

 planes of erosion also had a broad application in tectonic geology. Of 

 this Willis writes : 



"His patient and accurate field-work led to the discovery of the great, flat 

 overthrusts in the Paleozoic rocks of Georgia and contributed an entirely new 

 interpretation of overthrust faults to the literature of structural geology." 



Physiography of southern Appalachians 



The beginnings of Hayes's professional career were almost coincident 

 with the rise of the modern school of physiography. AYith his broad 

 interests, he could not but be influenced by this movement, though it was 

 entirely foreign to most of his previous experience. It is clear also that 

 Hayes's Alaska journey, made in 1891, of which more hereafter, had an 

 important influence in developing his interest in physiography. He was, 

 of course, like all geologists, thoroughly conversant with the publications 

 of the older pioneers in physiography, like Powell and Gilbert: but iu 

 1891 it was to the writings of Davis that he inade most frequent refer- 

 ence. Some of Davis's first papers dealing with this subject were both 

 presented and published in Washington, and this fact was an important 

 influence in directing the attention of the geologists of the Federal Sur- 

 vey to the systematic analysis of the genesis of land forms. As these 

 papers dealt with Appalachian physiography, they were of special interest 

 to Hayes and his colleagues of the Appalachian division, of which Bailey 

 Willis then had charge. M. E. Campbell, who was Hayes's assistant in 

 1889-1890, also became a keen student of physiography. The compre- 

 hensive plan of working out the physiography of the southern Appa- 

 lachians appears to have been first proposed by Campbell, but was carried 

 out as a joint investigation. In January, 1893, Hayes writes of this 

 research : 



"At intervals during the past three months, for the most part out of office 

 hours, Mr. Campbell and I have been engaged in bringing together all the 

 available data on the baselevels and development of drainage system in the 

 southern Appalachians." 



The results were published a year later as the ^^Geomorphology of the 

 southern Appalachians," a publication which placed the authors at once 



