103 



of the entire block. We can never sufficiently admire the 

 means, stupendous as they must have been, and yet magnifi- 

 cently simple, by which such a mass has been thrust out 

 from its parent bed and deposited in a position so strange, 

 and we may almost say, magical. 



The mineralogist is not favored in this region like his geo- 

 logical brother. So far as ascertained, the list of species is 

 small and the kinds not specially remarkable. He had been 

 asked whether rocks grow. The question may be variously 

 answered. In some cases, rocks certainly grow smaller if 

 the expression be allowable. The wind and frost- -all the 

 elements are wearing down the granite about us and the 

 figure of the ledges becomes much altered by this causo. 

 Rocks whose structure depends on the agency of heat can 

 have no increase of bulk afterward ; but such as limestone, 

 sandstone, bog iron ore, and chalk, the products of mere 

 accretion and pressure, may be all the time in process of 

 formation, or. as we miglit say, of growth. 



The distribution of shells is always interesting to the geol- 

 ogist, bearing, as it does, on the subject of fossil remains. 

 An exploration of the islands in Salem Harbor affords some 

 curious results, in the peculiar distribution of the genus 

 Helix. On House Island, near the Misery, arc found sev- 

 eral species, some of them in abundance. Eagle Island also 

 furnishes many specimens, but they differ materially from 

 those of the first locality. Helix albolabris, II. altemata and 

 H. hortensis are the principal kinds found at these places. 



C. M. TRACY of Lynn, said that although the list of min- 

 erals lound here was not large, yet some of them did not 

 lack importance. One cf the first, if not the very first, 

 establishments for the working of iron in this country was 

 at Saugus, and was supplied, as is believed, with bog iron 

 ore from the northern part of the town. Again, just east of 

 the place of meeting, lies the celebrated Lynn Mineral 



