50 BULLETIN OP THE 



marked by a line of cliffs in which are exposed nearly vertical 

 sections of formations denuded from the other side of the valley. 

 Most of the larger valleys of this region are of this character. 

 These are called paraclinal valleys. This gives three classes of 

 valleys having a general direction the same as that of the folds, 

 all called longitudinal valleys. Still other valleys were found 

 cutting across folds. These were called diaclinal. Others were 

 found running in a direction against the dip of the rocks and 

 entering into anticlinal or paraclinal valleys. These were called 

 contraclinal. 



Valleys were also found running with the dip of the formations, 

 and called conclinal. So three classes of valleys were found 

 having a general direction transverse to the axes of the folds, 

 and all called transverse valleys. And the three classes of lon- 

 gitudinal valleys, with the three classes of transverse valleys, 

 were designated as simple valleys. Other valleys weve found 

 which in parts of their courses might be refex'red to one of these 

 classes, and in other parts to some other class. These were called 

 complex valleys. And again, valleys were found having their 

 main course simple or complex, and having lateral valleys be- 

 longing to other classes. These were called compound valleys. 



The Yalley of the Colorado itself is formed by the coalescing 

 of two or more distinct systems of drainage. And this was 

 called a Grand Yalley. A tabular statement of the proposed 

 classification was made, as follows : — 



I Order: Yalleys conforming to geological folds, 

 II Order : Yalleys in formations not folded. 

 Ill Order : Yalleys superimposed upon folded formations. 

 The first order was divided into three sections : — 

 First Section : Simple Yalleys. 

 Second Section : Complex Yalleys. 

 Third Section : Compound Yalleys. 

 The first section, i. e. Simple Yalleys, was separated into two 

 divisions: — 



Division First : Longitudinal Yalleys. 

 Division Second : Transverse Yalleys. 

 Of the Longitudinal Yalleys there are three classes : — 

 First: Synclinal, 

 Second : Anticlinal. 

 Third : Paraclinal. 



