GEOLOGY — WILLIS. 1 95 



facts which favorable circumstances had enabled us to gather. Dur- 

 ing my stay in Berlin room was furnished me at the Geographic Insti- 

 tute, of which he is director, and its facilities for study were placed 

 at my disposal. We had frequent conferences, which led to a common 

 understanding of the facts and in general to agreement in views. 



Vienna. — At Vienna there are three scientists whose views were 

 sought : Prof. Edouard Suess, Prof. Albrecht Penck, and Prof. Victor 

 Uhlig. In preparing the volume of Das Antlitz der Erde which 

 describes Asia, Suess became peculiarly familiar with Russian reports 

 of exploration, but it was his preeminent position as founder of the 

 theories regarding mountain structure which are now dominant in 

 Europe which led me to lay before him the alternative hypotheses 

 based on observations in America and Asia. Penck, the interpreter 

 of European physiography, whose views, though original, are in 

 sympathy with American ideas, gave me the benefit of his wide 

 knowledge of the problems which I could but hastily scan. We made 

 several excursions together to typical localities in Austria. Uhlig, 

 to whom more than to anyone else we owe a knowledge of the geology 

 of the Karpathians, not only placed his data at my disposal, but also 

 accompanied me several days in the field. 



Among others to whom I became indebted in the course of scien- 

 tific work are Dr. Max Groll, of Berlin ; Professor Bruckner, of 

 Halle ; Professor Gavazzi, of Fiume ; Professors Marinelli and Dar- 

 nelli, of Florence; Professor Arturo Isso, of Genoa, and Professor 

 Kilian, of Grenoble. Special interest and courtesy were shown by 

 Prof. Johann Cvijic, of Belgrade, and through him by the Servian 

 authorities, in arranging conveniences for the trip down the Danube. 

 Professor Cvijic also accompanied me through Bulgaria and to Con- 

 stantinople. 



STUDIES IN MOUNTAIN GROWTH. 



Character of observations. — At the present time a report of the 

 studies in mountain growth must be limited to an outline of observa- 

 tions and their bearing, without adequate discussion of the evidence 

 or presentation of alternative arguments. There are two distinct 

 methods of investigation, the geologic and the physiographic, which 

 supplement one another and should be combined ; but the geologic, 

 dealing with internal structures, is frequently pursued to the exclu- 

 sion of the other, and the physiographic, being based on external 

 forms, tempts the general observer to draw inferences, even where 

 the underlying geologic relations are unknown. In either case a 

 partial conclusion alone can result. In their present state my 



