. The Canadian naturalist and geologist. Natural history -- Periodicals. 2ao Common HocJcs of the British Provinces, is not slaty, it correspouds in character -with the greenstones of the trr*p family, and lias been called primitive greenstone. It may be termed horn- blende rock. Some of tl'8se horubleudic masses may really have been volcanic rocks which have since assumed a more crystalline or metamorpliic texture. " Mica-schisty or Micaceous schist, is next to gneiss, one of the most abimdant rocks of the metamorpliic series. It is slaty, essentially composed of mica and quartz, the mic
. The Canadian naturalist and geologist. Natural history -- Periodicals. 2ao Common HocJcs of the British Provinces, is not slaty, it correspouds in character -with the greenstones of the trr*p family, and lias been called primitive greenstone. It may be termed horn- blende rock. Some of tl'8se horubleudic masses may really have been volcanic rocks which have since assumed a more crystalline or metamorpliic texture. " Mica-schisty or Micaceous schist, is next to gneiss, one of the most abimdant rocks of the metamorpliic series. It is slaty, essentially composed of mica and quartz, the mica sometimes appearing to constitute the whole mass. Beds of pure quartz also occur in this formation. In some districts garnets in regular twelve sided crystels form an integrant part of mica schist. The great bulk of the Laureutian rocks consists of the above three species Syenitic gneiss, Hernblende schist, and Mica schist. But in addition to these, the formation also includes many beds of white limestone, a rock identical in composition with the white marble, so much used for tombstones and other purposes in Canada and the neighbouring States. The white limestone is iuterstratified with the syenitic, gneiss, and other rocks. In some localities there may be seen hills of rock composed of beds of the limestone and syenitic gneiss, alternating with each other through a great thickness of strata. Sometimes there will be a single layer of lime- stone then a stratum of gneiss, then another of limestone, and so on for many yards in depth ; but usually from twelve feet to several hundred feet in thick- ness of each deposit is found without any intermixture of the other. The limestone is usually white, but often striped with grey bands. It is also at times somewhat reddish or flesh coloured, and frequently, as do many of the Laurentiau rocks, contains crystals of other minerals. Of these, we shall, in some future article, give more full particulars. The following wood cuts are intend
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