20 NEW YORK STATE MUSEUM 



the highest valley bottom immediately surrounding the Adirondacks. 

 Disregarding the loose, comparatively recent glacial deposits, the 

 eastern half of the Black River valley shows the very ancient 

 Adirondack (pre-Paleozoic) rocks only, while on the western side 

 there are early Paleozoic strata only piled up to a thickness of 

 1500 feet with slight westward tilt (see figure 12). These strata 

 are limestones, shales and sandstones. 



Mountains 



The mountains and valleys of the Adirondack region are the 

 present outward expression of an exceedingly long history. An 

 outline of this history will be presented in the next chapter, the 

 purpose now being to describe the principal topographic (relief) 

 features without much explanation of their origin. 



Viewed in a broad way, the Adirondack mountains and valleys 

 are very irregularly arranged, this being due largely to the exceed- 

 ingly patchy distribution of the relatively harder and softer rocks, 

 as explained below, the harder rock masses having stood out most 

 against weathering and erosion to form the mountains. There are 

 no long, distinct, approximately parallel ridges (so-called " ranges "') 

 such as characterize the Appalachians. In the southeastern half of 

 the Adirondacks there is a considerable tendency for many of the 

 mountain masses to be arranged as roughly parallel short ridges 

 with north-northeast by south-southwest trend. This structural 

 feature is due to the fact, as will be explained in the next chapter, 

 that this portion of the region has been highly fractured (faulted), 

 the principal fractures trending parallel to the north-northeast by 

 south-southwest ridges. There are, however, many exceptions to 

 this parallelism of mountain masses, while very few of the ridges 

 are as much as 10 miles long and many of them are not very 

 sharply defined as ridges because of notable variations in width 

 and altitude in individual cases. In spite of this moderate tendency 

 toward parallelism, the Adirondacks are, as the map (figure 4) 

 suggests, a jumbled mass of very irregularly shaped, relatively low 

 mountains. 



By far the greatest number of mountains rise from 1000 to 3000 

 feet above sea level; a considerable number reach altitudes of 3000 

 to 4000 feet ; while very few are over 4000 feet, the highest of all 

 being Mt Marcy in the east-central portion (Essex county). This 

 east-central portion contains the group of loftiest mountains in the 

 Adirondacks, most of the highest ones showing altitudes in feet 



