EXPLANATION OF THE PLATES. 



PLATE I. 

 It is designed to represent the valley of the Hudson at Albany, and the Helderbcrg range as it appears 

 from the high grounds in the rear of Grccnbush. The vallej' is colored yellow, and is a narrow 

 alluvial formation reposing upon the tertiary or Albany clay. The immediate rock, and which 

 appears at the Norman's kill, is the thick-bedded gray sandstone of the superior part of the Hudson 

 river group; it extends nearly eight miles west, before it disappears beneath the calcareous shales 

 of the waterlimes at the base of the Helderberg hills. The group which forms the Hclderberg 

 division appears in succession, and makes by itself a full and complete series, which ends with the 

 Onondaga limestone at New-Scotland. The superior part of the Helderberg range, as represented in 

 the panoramic view, is the Erie division. Upon the e.Ktreme left is the Catskill or Devonian division, 

 which is colored red. The Pentamerus and Delthyris shale crop out at the main terrace on the 

 right, and dip to the southwest. Still farther upon the right the Hudson river group, the thick- 

 bedded sandstone, interlaminated with a black slate, forms the slope as it extends itself towards the 

 Mohawk valley. The view is north and south. The lowest rocks belong to the Cham plain 

 division, the upper to the Catskill. The Ontario division is wanting in the series. 



PLATE n. 



The view is designed to exhibit some of the features of the Mohawk valley, particularly its vegetation. 

 The elm, with its pendulous branches and small and numerous ones upon the trunk, has the com- 

 mon shape and condition of the red elm of this valley. 



PLATE HL 



The country about Rochester is richly exhibited from Mount Hope. The view looks toward the north- 

 west. It is in Central New-York, and upon the argillaceous or wheat soils, that the splendid 

 American elms flourish and attain a great height. They often appear without branches or limbs, 

 until the trunk spreads as it were at once into a noble head. They form characteristic points in the 

 landscape. 



PLATE IV. 



The Catskill creek, for four or five miles, forces its way through a region excessively disturbed : it is 

 in fact a part of the great north and south fracture, in which insulated hills ofien appear, but still 

 formed of rocks which seem have been forced upward and broken from the adjacent strata. This 

 mass of Pentamerus rock forms a part of a segment of a great curve, the edges of v.'hich dip towards 

 the centre. The inferior, the Hudson river group, is the lowest mass, and dips rapidly beneath the 

 limestones. 



PLATE V. 



The panoramic view was taken from the northwest extremity of the Helderberg range, the observer 

 looking east. The valley of the Hudson occupies the extreme of the middle grounds, the river 

 itself appearing only at intervals. The foreground is occupied by the limestones of the Hclderberg. 

 The long narrow hills, with their narrow intervening vallies, appear in the back ground ; but the 

 distance is too great to exhibit their characteristics. 



4S* 



