DEVONIAN AGE. 26£ 



Gymnosperms before the age of Coal-plants ; and so there may have 

 been Fishes precursors of the age of Fishes. This is consonant with 

 the principles involved in the very nature of history. 



European geology, as far as developed, sustains the conclusions 

 deduced from the American : — that the Upper Silurian era, to its 

 close (with the exception above mentioned, if it be such), was an 

 era of small areas of dry land, — of continents mostly submerged, 

 though not necessarily at great depths, — of warm waters to the 

 poles, — of marine life,— of Mollusks and inferior Crustaceans as the 

 higher life of the seas, and the flower-like Corals and Crinoids as the 

 inferior life, and of Sea-weeds as the vegetation. 



AGE OF FISHES, OR DEVONIAN AGE. 



The Devonian formation was so named by Murchison and Sedg- 

 wick from Devonshire, England, where it occurs and abounds in 

 organic remains. Both in America and other countries the beds 

 pass into those of the Silurian by an easy transition. Yet they still 

 mark a new epoch in the progress of life, and thus stand apart in 

 the system of geological history. 



The periods and epochs in the American Devonian, as deduced 

 from the series of rocks laid down by the New York geologists, are 

 as follow : — 



5. Catskill Period (12) Catskill Red Sandstone (12). 



4. Chemung Pebiod (11) I 2 ' Chemun 9 epoch-Chemxmg group (11 b). 



{ 1. Portage epoch — Portage group (11 a). 



{3. Genesee epoch — Genesee beds (10 c). 

 2. Hamilton epoch — Hamilton group (10 b). 

 1. Marcellus epoch — Marcellus group (10 a), 

 r 3. Upper Helderberg epoch — Upper Helderberg 



2. CORNIFEROUS PERIOD (9). J „ g , r ° 7 UP ^ ^' 



I 2. Schoharie epoch — Schoharie grit (9 b). 

 y 1. Cauda- Galli epoch — Cauda-Galli grit (9 a). 

 1. Oriskany Period (8) Oriskany sandstone. 



The formations of the first and second periods are sometimes 

 designated the Lower Devonian, and those of the third, fourth, and 

 fifth periods, the Upper Devonian. The Corniferous period was the 

 great limestone-making period of the Devonian age in America. 

 The rocks of the succeeding periods (Upper Devonian) are mostly 

 shales or sandstones, with only subordinate layers of limestone. 



