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[Assembly 
Geology, A science which has for its object the investigation of the 
structure of the earth and the materials of which it is composed. 
Connected with these investigations, are deductions which may Be 
derived legitimately from the known influence and cfftcts of causes; 
these are employed as expressions of the modus operandi by which 
the earth has been brought to its present state. 
Gneiss. A stratified primary rock, composed of quartz, feldspar and 
mica. 
Granite. An unstratified rock, composed of quartz, feldspar and mica. 
GrG7(wacke, grnywacke. The name was orignally applied to a rock 
composed of grains and pebbles cemented together by clay. It be- 
longs to the tiansition scries. The name is applied also to a group 
of rocks in the same series, consisting of sandstone, slates or sh.dt s, 
alternating with liu.estone, sandstone, &c. The term is rather inde- 
finite, yet very frequently used. 
Gree7i sa7id. Beds of sand, sandstone, limestone and marly clays, inter- 
mixed som( what with greenish particles, belonging to the cretaceous 
perio<l anil situated beneath the true chalk. 
Greensicne. A variety of tra[), composed of feldspar and horneblende. 
Grit. Coarse grained sandstone. 
Gypsum. A mineral composed of sulphuric acid and lime. 
Hornblenile. A mineral, usually of a dark green colour. Crystallizing in 
long slender prisms. 
Ilornsicne. A siliceous translucent mineral, resembling flint, but tough 
and more diflicult to break. 
LicanJesce/it. White hot — a degree of heat more intense than that at 
redness. 
Icfbcri^. Floating masses of ice. 
Lht/iycscrurus. A fossil reptile, intermediate between the crocodile end 
fish. A fish lizard. 
Induction. A consequence, conclusion, or inference, or some general 
])iinciple drawn from facts or phenomena. 
la- situ. Original position. 
Isdhermal. Equality of temperature. Zones, lines, &c. where an equa- 
lity of temperature prevails are called isothermal. 
Lacustririe^ of, or belonging to, a lake. 
jMniince. Plates, sometimes used as synonymous with layers. 
Landslip. Land which has slidden down an inclined plane, from its po- 
sition in a bank or terrace. It is generally produced by water, which 
either undermines the mass of earth, or insinuates itself into it, so as 
to render it semi-fluid. 
Line cf Bearing. The point of compass to which the anticlinal ridge or 
line runs, or is directed. When the anticlinal ritlge cannot be deter- 
mined, the line of direction may be known by asceitaining the inter- 
section of the planes of the strata with the plane of the horizon, that 
will be the line of bearing. 
Litholcgical. The character of a rock or formation considered with refe- 
rence solely to its mineral composition. 
Lignite. Wood partially carbonized in the earth; it usually retains the 
vegetable structure. The change does not seem to have been effected 
by heat, but is the result of some chemical process, as the action of 
pure sulphuric acid in some instances, and of water in others. 
