280 GEOGNOSY OF THE APPALACHIANS. [XIII. 



sometimes nearly pure feldspar, but often include small portions 

 of hypersthene, pyroxene, or hornblende, the former two 

 being sometimes associated in the same specimen, and in con- 

 tact with each other. A black mica (biotite), red garnet, epi- 

 dote, chrysolite, and menacannite (titanic iron) are frequently 

 present in these rocks ; quartz, however, is rarely seen, and then 

 only in small quantities. Through an admixture of the first- 

 named minerals these norites pass into hyperite, diabase, and 

 diorite. The norites vary in texture, being sometimes coarsely 

 granitoid, and at other times fine grained and nearly impalpable. 

 The coarser varieties often present large cleavable masses, show- 

 ing the striae characteristic of the polysynthetic macles of the 

 triclinic feldspars, and sometimes exhibit a fine play of colors, 

 as in the well-known specimens from Labrador. A gneissic 

 structure is well marked in many of the less coarse-grained 

 varieties of norite, and the lines of bedding are shown by the 

 arrangement of the various foreign minerals. Although norites 

 predominate in the Norian series, they are found in the area 

 of these rocks which is seen to the north of Montreal to be in- 

 terstratified with beds of micaceous orthoclase-gneiss, quartzite, 

 and crystalline limestone, not unlike those met with in the 

 Laurentian and White Mountain series. It was from their dis- 

 tribution in this region that Sir William Logan was enabled to 

 show that the rocks of the Norian series rest unconformably 

 upon the gneisses and limestones of the Laurentian. Further 

 evidence of the same kind was obtained by Mr. Richardson, in 

 1869, on the north side of the Gulf of St. Lawrence, where 

 rocks of the Norian series were found to lie in discordant 

 stratification, and at moderate angles on the nearly vertical 

 Laurentian gneiss. The norites may be readily studied in 

 Essex County, New York, where they reach the shore of Lake 

 Champlain just above the town of Westport, and include the 

 great deposits of titanic iron ores of this region. The titanic 

 ores of Bay St. Paul, Lake St. John, and the Bay of Seven 

 Islands, in Canada, also occur in Norian rocks. In all of these 

 localities they appear to be directly superposed on the Lauren- 

 tian ; but in the vicinity of St. John, New Brunswick, a small 



