GEOLOGY 145 



men and for different localities that they have not been re- 

 garded as accurate even within broad limits. Geologists, like 

 biologists, have been very insistent on having plenty of time 

 allowed them for their purposes. This has been denied them 

 by physicists on the basis of mathematical calculation of facts 

 of heat radiation. Physicists, assuming that the existing earth 

 temperature is the result of radiation from a former much 

 higher stand, and that the rate of radiation can be determined 

 and the existing temperature reached by calculation, assert 

 that it is an easy matter to compute backward to the time 

 when the earth was too hot to permit organic life to flourish. 

 It was pointed out, however, in the discussion of the planet- 

 esimal hypothesis that the earth probably was never in a 

 molten condition, that its existing temperature is not wholly 

 a stage in a progressive decline, and that so far as temperature 

 is concerned life may have existed on the earth even before it 

 had grown to one-half its existing size. 



The discovery of the action of radium has also pro- 

 foundly modified the conclusions that may be arrived at 

 through mathematical computations such as those just re- 

 ferred to. The amount of radiant matter originally in the 

 earth may have increased its period of life to practically any 

 extent whatever. The geologist, therefore, may have the su- 

 preme satisfaction of saying to the physicists and mathemati- 

 cians: *T told you so." Nevertheless, geologists have not yet 

 discovered a geological time scale that can be applied to the 

 time existence of the earth. 



I have stated and discussed some of the principles that 

 have already been worked out and some of the problems that 

 are yet unsolved. There is an abundance of work. The la- 

 borers in the field are of many degrees. Most of us are mere 

 brickmakers. We labor at the individual units ; we have our 

 eyes on the ground and are so intent on our own brick, our 

 own fact, that we fail to see, nay we are often not even inter- 

 ested in, what our neighbor is doing or what relation his brick 



