92 ANNALS NEW YORK ACADEMY OF SCIENCES 



rock steps, and various other features due to glaciation are of frequent 

 occurrence (see Plate I, Fig. A). 



Since the disappearance of the glaciers, erosion has been slight. The 

 streams have cut through the loose moraines in some places, but where 

 they have been flowing on solid rock beds, they have cut but faint notches. 

 These modifications are negligible as compared with the preglacial and 

 glacial erosion which produced mature dissection. 



Stratigraphy 

 introductory statement 



The first works of importance on the general stratigraphical succession 

 in the Wasatch Mountains are those of the King^ and Hayden* surveys 

 in the late seventies. They are to-day the only comprehensive account 

 that we have dealing with the great range of sediments there exposed. 

 Being general in their treatment, they have left many details to be sup- 

 plied by closer investigations, such as are carried on within smaller quad- 

 rangles where the necessary time is taken to work out structural problems 

 as well as to observe the general sequence of beds. American stratigraphy 

 offers many examples of the mistakes that are so easily made by follow- 

 ing the law of superposition without due regard to structure. Unrecog- 

 nized repetition of beds by folding and faulting has often led to serious 

 errors in estimating the real thickness and succession of formations. 

 Within the limited time that was allotted to the comparatively few 

 workers on these early surveys, a wonderful amount of field work was 

 done, and magnificent reports, well illustrated with maps and sketches, 

 were issued, which, though they are now known to be wrong in many 

 cases, still serve as the best introduction to the systematic geology of the 

 range. 



In presenting a generalized account of the stratigraphy of the Wasatch 

 Mountains, the Fortieth Parallel geologists seem to have taken the sec- 

 tions which showed the thickest development of the rocks of the various 

 systems. The sections exposed in Weber Canyon and a few miles to the 

 north in Ogden Canyon, together with those found in Big and Little 

 Cottonwood Canyons, sixty miles to the south, seem to have been chosen 

 as the types for the Paleozoic rocks. Especially the latter seems to have 

 made a wonderful impression upon King, who introduces it thus : "I will 

 now give a section observed between the mouth of Cottonwood Canyon 



3 IT. S. Geol. Expl. 40th Par., vols. I and II, 1877, and Vol. Ill, 1878. 

 * IT. S. Geog. and Geol. Surv. of the Territories. 



