'201 TERTIARY SYSTEM. 



Mate of the beds, they are liable to slide down in mass. This movement maj extend for 

 Bome considerable distance, and sometimes the sand lias flowed into and filled the ezca- 

 ms. There are, also, occasional faults in the clay ami sand IkhIs; and, as in othei 

 cases of n like nature among rocks, these fanlr- give origin to Bprings. 



In the excavations in the citj of Albany, a boulder is sometimes found in the claj , but 

 alwaj s near the top of the formation. This assertion is intended io lie confined to tin- true 

 mentarj beds: ii dues not apply to the drift beds, which arc sometimes exposed in 

 this valley. The) repose generally upon the rock, and belong to the base of the forma- 

 tion, <>r to that moderate drift period which followed the deposition of the day and sand 

 beds whose strata are uniform and unbroken, and which are comparatively free from 

 coarse sand, gravel and boulders. 



The sand of this formation is yellowish, porous, and rather barren. There are beds, 

 however, which are quite the reverse of this, and are really remarkable ; they form the 



excellent moulding sand so well known in the vicinity of Albany. It is a sand which is 

 ily mixed with loam, and which retains a certain amount of moisture under all cir- 

 cumstances. Even when exposed in heaps in dry weather, ii appears moist beneath the 

 surface, and when pressed in the hand, retains the shape and form given it. This sand, 

 too, forms an excellent Boil, of which we shall have occasion to speak hereafter. 



§ 3. Marl and peat. 



re dismissing those formations which have been called tertiary and post-tertiary, it 

 i* proper to --peak of the deposits which are considered by all geologists as the most recent, 

 and which really are the proximate formations that connect the modern deposits with the 

 ancient ; the present, with the past; and in which geological changes hear an aspect more 

 real than those of the Carboniferous or Silurian era. It is bj means of the fossils of a period 

 just anterior to the present, and which is not to be regarded precisely as a tangent to it, 

 but rather as forming with it a continuous portion of a great circle, that we may familiarize 

 our minds with the nature of those peculiar changes and phenomena which clothe the 

 h BUnrj of the earth with so much interest. Just before us, there lived races of animals, 

 whose forms and whose habits scarcely differed from those which are now familiar to us: 

 they were really members of different families at present existing and known to us, 

 having affinities and relationships with them of the closest kind. Knowing the living and 

 the present, we also know the dead and the past. Conjoined in both periods, we have 

 the last term of a series, from which we may travel hack to the remoter periods, and trace 

 up the analogies as they have been successively developed. We judge the past by the 

 prevent ; and from the store of knowledge accumulated by modem discovery and modern 

 induction, we are ( nabled to Bupplj many of the links which are wanting to complete 

 the system of a perfect scale of being, such as shall represent the whole of life and 

 organization as it was made for the earth. The chain is complete, and its extremities are 

 united in one eternally revolving circle of life. It looks an ocean of being, formed by the 



