AGRICULTURAL MUSEUM. 



[The Collection of Rocks, Minerals and Fossils, in the State Cabinet, was 

 obtained during the Geological Surveys of Massachusetts, between the years 

 1830 and 1840, by Dr. Edward Hitchcock, State Geologist, and he has 

 furnished the following statement in regard to it. Later additions have been 

 made and the entire collection has been rearranged and relabelled by him.] 



Amhekst College, December 1, 1858. 



This Collection was made at different periods while the two Geological 

 Surveys of the State were in progress, so that three sets of numbers were 

 used, making the Catalogue appended to the Final Report quite incon- 

 venient. A diff'erent arrangement is now practicable, and has been adopted. 

 Each rock has now a separate series of numbers, so that additions can here- 

 after be made to them by merely extending that series, without disturbing the 

 regular order. 



The progress of Geology, also, since the Surveys were made, make some 

 changes desirable. Additional discoveries have, in some cases, led us to alter 

 the place of rocks upon the geological scale. But the doctrines respecting 

 the Mctamorphisni of Rocks have produced the greatest alterations. Probably 

 all geologists now agree in the opinion that all the rocks in the earth's crust, 

 stratified and unstratified, have undergone important modifications through 

 the influence of heat and water — that is, are Metamorphic. But the inquiry 

 as to the nature and condition of the rocks before their metamorphosis is a 

 much more difficult subject, on which geologists will have different opinions. 

 Some take the ground that all stratified rocks were once fossiliferous ; and it 

 is quite common now to maintain that such was the case with all those in 

 Massachusetts and New England generally. Others believe that thick deposits 

 of stratified rocks were made before the creation of animals and plants, and 

 these they call Hypozoic Rocks. That they have been subject to metamor- 

 phosis is admitted, but it has been a change from a less to a more crystalline 

 condition, and not from fossiliferous to non-fossillferous. This latter change, 

 also, it is admitted, has passed upon some rocks, making them exceedingly to 

 resemble the Hypozoic Rocks. That this change has been extensively pro- 

 duced upon the rocks of Massachusetts can hardly be doubted. But I am 

 not prepared to say that we have no hypozoic strata protruding through the 

 metamorphic, which were once fossiliferous. Nor can I as yet identify all the 

 metamorphic strata with the original Silurian and Devonian formations out of 



