194 WALKS AND TALKS. 



The Potsdam SaDdstone from northern New York to Min- 

 nesota appears to be the lowest formation above the Eozoic 

 crystalline rocks. The copper-bearing rocks are older, but it 

 is not yet decided whether we should regard them as embraced 

 in the Palaeozoic System or not. There is also, in Wisconsin 

 and Minnesota, a massive quartzite formation underneath the 

 Potsdam Sandstone; but as it is not fully proved to contain 

 any fossils, we are not certain whether to call it Eozoic or not. 

 But in Vermont, in eastern Massachusetts and in New Bruns- 

 wick, are slates which underlie the Potsdam and contain fos- 

 sils. (" Acadian " or "St. John" Group). Some of these were 

 Trilobites ten to twenty inches long. 



Down in these lowest Palaeozoic strata we find also, other 

 remains of animal types. Here for instance, are " chambered 

 shells " the grandfathers of those described in the last Talk. 

 We find here Or-ihoc'-e-ras, as well as some marked deviations 

 from it. Here are the oldest examples known of this type. 

 Here, we might say, was its first introduction to the world ; 

 and we might begin to query how it came here. We should 

 be inclined to think it was an abrupt introduction, without 

 predecessors gradually more and more simple as we should trace 

 them into remoter ages. If an abrupt introduction, it was 

 not an evolution from some older form, because evolution pro- 

 ceeds by gradual transitions. Such is the conclusion of some 

 scientific men ; and if we were obliged to form a conclusion 

 on the whole question from the facts connected with the first 

 appearance of chambered shells, I think we should all say 

 they did not appear according to the method of evolution. 

 We must be candid, however, and consider all the circum- 

 stances. We only wish to ascertain how the facts were not 

 to make ourselves think them different from the reality. If 

 chambered shells appeared according to evolution, that is the 

 thing we want to know ; and it would be a pity to make ourselves 

 believe something not in accordance with God's ordination of 

 things. Now we know full well that the rocks older than the 

 Cambrian have been subjected to such actions since they were 

 deposited as ocean-sediments, that their aspect is totally trans- 



