36 NEW YORK STATE MUSEUM 



life in the Grenville ocean, however, we are certain that organisms 

 of some kind must have existed as proved by the scattering flakes 

 of graphite through many of the strata, especially the limestone. 

 All that is now left of the organisms is the carbon, and this has 

 been crystallized into graphite so that no original structures what- 

 ever are retained. Even though we do not know whether these 

 organisms were plant or animal, the fact that life existed on our 

 planet so many millions of years ago is a fact of very great 

 importance. When we look at the shiny black scales of graphite in 

 a piece of Grenville rock, we can truthfully say that we are gazing 

 upon vestiges of the earliest known organisms which ever lived upon 

 the earth. Graphite thus disseminated through stratified rocks must 

 have been of organic origin. Anthracite coal, which is chemically 

 very similar to graphite, occurs in the late Paleozoic strata of 

 Pennsylvania and is there definitely known to have been derived 

 from plants through the process of carbonization. Graphitic anthra- 

 cite of like origin occurs in Rhode Island. The earth's first organ- 

 isms must have been plants, because animals ultimately depend upon 

 plants for their existence. The oldest known clearly preserved 

 fossils are Algae or sea weeds from the Proterozoic. Hence it 

 seems likely that the graphite of the Grenville strata represents the 

 remains of plants, probably of the simple sea-weed type.. This by 

 no means proves the absence of animals from the Grenville ocean, 

 because animals with soft parts only would have left no record, 

 while shells would have been destroyed by solution and crystalli- 

 zation under the conditions to which the strata were subjected. 



Earliest igneous rocks and their history. After the accumu- 

 lation of the Grenville sediments, igneous activity took place on 

 grand scales, when great masses of molten rock were forced 

 (intruded) into the sediments from below. At least two distinct 

 times of very early, large scale igneous activity have been dis- 

 covered. The general effect was to break the Grenville up into 

 patches. The present distribution and mode of occurrence of these 

 igneous rocks show that the molten masses broke into the Grenville 

 strata in a very irregular manner. In most cases the Grenville 

 rocks were pushed aside by, or tilted or domed over, the upwelling 

 molten floods; in many cases the molten materials under great 

 pressure were intimately shot through the Grenville strata; often 

 large or small masses of strata were caught up or enveloped (as 

 inclusions) in the molten floods ; in some cases there appears to have 

 been actual local melting or assimilation of Grenville rocks by the 

 molten instrusions ; while in still other places large Grenville bodies 



