Annual report . tlyof medium-grained, granular quartz, or quartzite, of a pinkish-grey color; others arepure white, coarser in grain, and resemble vein quartz. In parts of the belt thesequartzite pebbles make up almost the whole conglomerate, the matrix being sandy,micaceous or calcareous; but most of the belt consists essentially of a grey to dark-colored gneiss with mica and hornblende and at times garnet. In this gneiss it is diffi-cult to recognize with certainty any pebbles except quartz. Although the quartzite andgranular quartz pebbles make up most of the conglomerate, a few granite, li
Annual report . tlyof medium-grained, granular quartz, or quartzite, of a pinkish-grey color; others arepure white, coarser in grain, and resemble vein quartz. In parts of the belt thesequartzite pebbles make up almost the whole conglomerate, the matrix being sandy,micaceous or calcareous; but most of the belt consists essentially of a grey to dark-colored gneiss with mica and hornblende and at times garnet. In this gneiss it is diffi-cult to recognize with certainty any pebbles except quartz. Although the quartzite andgranular quartz pebbles make up most of the conglomerate, a few granite, limestone,and dark-colored gneiss pebbles have been found. In all cases the pebbles have been flattened so that their longer diameters aregenerally several times their shorter ones, Fig. 38. Regarding the thickness of the conglomerate it can merely be said that the hillscomposing this rock rise to a height of about one hundred feet. This has not muchsignificance because little evidence of original bedding Fljf. .•S. Pebble elongated by pressure, Hastings conglomerate. Palmerston township, Frontenac county. A thin section of the gneissic or schistose matrix of the conglomerate shows it tobe made up of green hornblende, quartz, biotite and a little plagioclase feldspar, all ofthe constituents being fresh. Much of what has been classed with the conglomerateconsists of similar gneissic material containing few recognizable pebbles. Under the microscope, a pebble of gYanular quartz, or quartzite, similar materialto that which makes up most of the conglomerate, is seen to consist of interlockinggrains of quartz together with a little sericite and iron ores. A thin section of a medium-grained, pink granite pebble shows it to be made upor twinned and untwinned feldspar, and quartz. The feldspar is partly altered to sericiteand calcite. The occurrence of granite pebbles in the conglomerate is rare. Relation o) Hastings conglomerate to Qrenville limestone and Laurentian —The e
Size: 2311px × 1081px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectminesandmineralresou
