308 



Scientific Geology. 



Limestone of Whitingham, Vt. 



This bed of limestone, as may be seen by the map, approaches 

 nearly or quite to the north line of Massachusetts, and lies near the 

 junction of a range of talcose slate and gneiss. It is stratified, and 

 the dip is not far from 30° west, the direction being north and south. 

 By following down a small tributary of Deerfield river, which has 

 laid bare this limestone in the southwest part of Whitingham, a good 

 opportunity is afforded for examining its characters. It is white 

 and decidedly crystalline, though often containing bronze colored 

 mica, and sulphuret of molybdenum in small plates. I found associ- 

 ated with it, also, actynolite, common augite, and mussite. Though 

 a mile or two in length, the breadth of the bed is very inconsiderable. 

 Its geological associations render it certain that this is one of the old- 

 est varieties of limestone. 



About 16 miles north of this bed, at the iron and gold mine in 

 Somerset, is a very elegant variety of dolomite, occurring in beds in 

 talcose slate. Some of it exceedingly resembles the purest loaf su- 

 gar. (Nos. 483, 484.) 



Limestone in Bolton, Boxborough, Littleton, Acton, Carlisle, and 

 Chelmsford. 



The geological situation of these limestone masses and their min- 

 eral characters are so similar, that one description will embrace them 

 all. They all correspond to the description which Dr. Macculloch 

 gives of the limestone of Tirey, one of the Western Islands of Scot- 

 land. " It is," says he, " improperly called a bed, as it is only an 

 irregular rock lying among the gneiss without stratification or con- 

 tinuity. In this respect it resembles the greater number of primary 

 limestones found in gneiss and mica slate, and may be considered as 

 a large nodule."* It will be seen by the map that all these masses 

 are in a gneiss formation, which, however, often passes into mica 

 slate, and contains numerous protrusions and veins of granite. The 

 dip and direction of the gneiss surrounding the limestone are visible 

 at nearly all the quarries : but the limestone itself rarely exhibits any 

 distinct marks of stratification. And as every one of these localities 

 contains a quarry, a good opportunity is presented for examining the 

 structure of the rocks. 



* Western Islands, Vol. 1. p. 48. 



