COUNTRY EOCKS 469 



limestone inclosed in the usual, well bedded mica schists. The ortho- 

 gneiss seems to have been uniformly a common biotite granite. 



Wherever observed, bedding and schistosity are parallel in the meta- 

 morphosed sediments. The dip is very seldom as low as 60° and is gen- 

 erally vertical. As indicated in figure 1, the strikes vary from north 30° 

 east to north 80° east, with an average near north 45° east — the Appa- 

 lachian trend. Because of the strong contrasts of the micaceous, quartz- 

 itic, and orthogneiss bands in their degrees of yielding to weathering 

 agents, the usual outcrop of these steeply dipping beds is strikingly fur- 

 rowed. 



The age of the sediments is quite unknown, and no definite hint has 

 yet been forthcoming as to the date or dates of the various intrusions. 

 There is no reason for assigning any of the rocks to a date later than the 

 Precambrian. 



Summary of Field Relations 



Outcrops in Litchfield are relatively rare. Hence thorough search by 

 several observers has not yet afforded the data for a complete account of 

 the litchfieldite. Judging from the visible masses and from the number 

 and distribution of boulders, it is tolerably certain that there is no large 

 mass of litchfieldite in the region. The celebrated boulders seem to have 

 been derived from short, sill-like pods injected into the prevailing crys- 

 talline schists. The invisible lenses are probably little larger than the 

 two so far discovered and have lengths measuring tens of meters or, at 

 most, hundreds of meters, and maximum widths of a few meters or tens 

 of meters. 



The largest single injection observed, at C (figure 1), is a highly alka- 

 line, but nephelite-free, syenite. This, like other syenite masses and like 

 the much more abundant quartz pegmatites, seems to have been injected 

 concordantly with the layering of the schists, though with local cross- 

 cutting. The igneous rocks may have been intruded before the upturning 

 of the sediments. 'No information is yet at hand as to the precise condi- 

 tions for the metamorphism of the various formations. Before the sye- 

 nites and litchfieldite were injected the sediments seem to have been com- 

 pletely recrystallized, possibly through static metamorphism. The rela- 

 tive importance of dynamic metamorphism is most uncertain. 



The coarse grain and general mineralogy of these igneous rocks strongly 

 suggest that magmatic gases were largely concerned in their emplacement 

 and in the concentration of the alkalies. Cancrinite in the litchfieldite 

 and calcite, probably primary, in the soda-syenite tend to show that car- 



