10 J. W. Goldthivait — Glacial Cirques 



growth ought greatly to exceed the lateral growth, unless the 

 joints are so placed that they check the head ward recession 

 and promote lateral recession of cliffs at the ravine heads. So 

 far as we could see, in our examination of the joint planes, no 

 such influence is apparent. A second objection to this theory 

 of the origin of the ravines lies in the presence so close 

 together of the two contrasted types of valley, the narrow- 

 headed Y-shaped gorge and the bowl-shaped trough. Take 

 for example the case of Snyder Brook valley and the two 



Fig. 4. 



Fig. 4. View across the head of Tuckerman Ravine to Mt. Washington. 

 Photograph by Shorey. The sharp rim and steep walls of the cirque are 

 strongly contrasted with the subdued slopes of the cone of Washington and 

 the surrounding lawn. 



gulfs between which it lies. If Cold Brook, aided by frost 

 and landslides, could have eaten out the great amphitheater 

 which lies at the head of King Ravine, Snyder Brook, which 

 is approximately equal to Cold Brook in volume, ought to 

 have done a similar piece of work. There is no reason to sup- 

 pose that the mica schist at the heads of King Ravine and 

 Bumpus Basin is any more favorably jointed or more easily 

 eaten out than that around the head of Snyder Brook. To 

 attribute the difference between Snyder valley and the two 

 troughs to abnormal jointing lays upon him who w r ould urge 



