150 FARMERS' INSTITUTES. 



times — of ever increasing fertilization, through a natural process of green 

 manuring, and from its thorough grindiug, stirring, and mixing by the grand 

 ice plows, was destined to become, as we know it has become, one of the most 

 fertile regions of tiie world. As we have seen, tlie geologist had only to study 

 the rocks of our Northern Peninsula to predict as did the remarkable and 

 greatly lamented Iloughton, that valuable metals would reward the prospector 

 in that part of our State. So likewise the study of the geology of Southern 

 Michigan would make as safe and certain the prediction of a rich and lastingly 

 fertile soil overspreading its broad acres Add to these facts the great bi-nds 

 in the rock strata that formed a permanent resting place for the great lakes 

 -which will ever temper the winds of this favored portion of the earth, and 

 we quickly comprehend the magnitude of nature's gifts to us in the wondrous 

 geological formation of our beloved State. As one would suppose, so we know, 

 that agriculturally considered she has no superior. 



Before closing this address let me call attention to the fact that the Michigan 

 .area in the oldest geologic time was a basin, having its center and deepest por- 

 tion near the center of the Lower Peninsula. Thus the rock areas reMresentina: 

 the different periods from oldest to later, even to the coal bearing rocks, the 

 last formed of the old time life strata, occurs here in rings near the close of 

 this old time life period. This Michigan area, then mostly out of water, became 

 the seat of an inclosed sea, with but a partial and constricted communication 

 with the ocean outside. The rocks forming the tioor of this inclosed sea w^ere 

 formed in deep water, and were thus of a shaly or clay formation, and so were 

 impervious to water. Hence for millions of years this central area of Michigan 

 was shut off from the ocean, and as its waters were evaporated the salt and 

 gypsum — plaster — were thrown down. And to this fact we owe the presence 

 of the gypsum and salt dejwsits whicli are destined to beccne more and more 

 a source of wealth to our people. AVithout the inclosed sea resting for ages 

 ujx)n our fair peninsula, the source of these valuable products would not have 

 existed. Without the clay sub-stratum the salt could not have been withheld. 

 As it is we have a vast mine of salt beneath us, which may be tapped in almost 

 any part of our Southern Peninsula, though at greater and greater expense as 

 we recede from the layer of rocks on which it rests. Later this inclosed sea 

 became drained, and was replaced by the great marsh area, in which the luxu- 

 riant vegetation was massed, and afterwards converted into coal. As tliese coal 

 rocks were the uppermost strata for long ages they were washed by old time 

 streams, and were afterwards torn by the glaciers. So we may never hope to 

 find our coal regions of equal value with those of many other porti'jus of the 

 country. Yet these added to the variety of the rocks from which our soil 

 originated, and may yet become the source of no inconsiderable wealth. 



Thus we see that this grand science which opens up so wondrous a history 

 has special interest to Michigan, and especially to the Michigan farmer, for it 

 shows him that the resources, from which spring the generous wealth and 

 2)rosperity of his State, can not be ephemeral, for they were fixed in the very 

 foundations of the earth, and were considered when tiic world wa^ planned. 



Mr. : Did all our small boulilers come from Lake Superior ? 



Prof. Cook : Yes; except, sandstones, whicli belong here. All hardheads 

 .and granite came from Lake Superior 



Mr. : Is there such a thiug as a stone growing? 



Prof. Cook: Yes, in geologic beds. 



Query : I mean liardheads, here. 



Prof. Cook : No. 



