The Geology of Hingham. 



17 



Explanation of Names of Formations, etc., mentioned in the Tables above. 



Pyroliihic. From the Greek, fire-stone. 



Arclwan. Ancient; the beginning. 



Azoic. Without life. 



Eozoic. Dawn of life. 



PaUeozoic. Ancient life. 



Mesozoic. Middle life. 



Ccenozoic. Recent life. 



Primordial. First in order. 



Silurian. Geographical, first applied to 



rocks of Siluria. 

 Devonian. Geographical, first applied to 



rocks of Devonshire. 

 Carboniferous. Having the great coal 



fields. 

 Cretaceous. Latin, for chalky. 

 Triassic. Named from a series of three 



kinds of rocks. 



Jurassic. Geographical, from rocks of 

 Alt. Jura. 



Permian. Geographical, from rocks of 

 Permia, an ancient kingdom of Russia. 



Tertiary. Adopted from old classifica- 

 tion, when the terms Primary, Second- 

 ary, and Tertiary embraced ail the rock 

 formations. 



Corniferous. From Latin cornu, horn, and 

 fero, I bear, the rocks bearing seams of 

 hornstone. 



Quaternary. From Latin qnatuor, four, 

 applied to strata following Tertiary 

 (third). 



Salina. From its salt-bearing brines ; 

 salina, in Latin, being a place where 

 salt is made. 



Other names geographical of known localities will not need explanation. 



Pyrolithic Time. — As the name denotes, the Pyrolithic for- 

 mations were igneous only, for the condition of the molten, but 

 gradually cooling globe admitted of none other. The immense 

 period required for any approach to stability of the surface must 

 have witnessed constant changes upon it, and over and over again 

 must the earlier incrusted portions have been broken up and re- 

 melted as they became from time to time, through the shrinking 

 consequent upon refrigeration, submerged in the incandescent 

 sea. At length when consolidation of the surface had increased, 

 rocky masses undoubtedly appeared above the general level, but 

 these were necessarily of a different character from any now 

 known. They were the truly primitive rocks, and it is very 

 doubtful if any trace of them can be found on the earth. 



Archaean Time. — Previous to the formation of the rocks of. 

 Archaean Time, the cooling of the globe had proceeded to a de- 

 gree allowing the existence of water in the atmosphere and its 

 deposit upon the surface. Of its earlier rocks we can know as 

 little as of those of Pyrolithic Time, for all now recognized appear 

 to be the result of the wearing down of pre-existing formations, 

 the deposit of their debris in the form of sands and clay as sedi- 

 ments in water, and the subsequent crystallization of much of the 

 material into gneisses, mica slates, etc. Other rocks of the time 

 are conglomerates, sandstones, and clay slates. 



There is evidence that both vegetable and animal life existed 

 in this early time, but only in its lowest forms. 



Paleozoic Time ; Silurian Age ; Primordial Period. — The 

 rocks of this period were formed from the wearing away of those 

 of Archaean Time, and the reconstruction of the material into new 

 strata. Great interest is felt in these because, so far as clearly 

 shown, they contain impressions of the remains of the first organ- 



VOL. I. — 2 



