No. 200.] 
GLOSSARY OF TECHNICAL TERMS. 
Alluvium. A recent deposit of earth, sand, gravel, peat, &c.; the term 
is applied to depositions which are now accumulating, as at the mouths 
of rivers, &c. 
Jllum rocks. Rocks which, by decomposition, form alum, . 
Amorphous, Bodies devoid of a regular form. 
Amygdaloid. A rock more or less cellular in its structure, and at the 
same time abounding in cavities in the shape of an almond. It is 
one of the class usually called Trap rocks. 
Anticlinal axis^ ridge j Sfc, The line from which the strata of any for-^ 
mation dip in two directions, like the roof of a house. 
Augite. A simple mineral of variable colours, passing from white through 
gray, green and black of different shades. It is a constituent of many 
volcanic and trappean rocks, limestone, granite, &c. 
Basalt. A black or grayish black compact rock occurring frequently 
in a columnar form, as at the Giant's Causeway in Ireland. Many 
geologists consider it to have been formed by the fusion of augitic and 
feldspathic rocks under great pressure, as at the bottom of an ocean 
or deep sea; hence its compact structure. 
Basin. Deposits lying in a hollow or trough-shaped excavation, are said 
to occupy basins. 
Bed. A mass of mineral matter lying between the layers or strata of any 
rock. 
Bitumenj bituminous^ ^c. An inflammable substance which presents it- 
self under two forms, a solid and liquid; when in the former state^ it 
is called asphaltum. In its liquid state, it is like tar. Seneca oil is 
an example of it. Coals^ slates, limestones are often bituminous. 
Blende. A German name for sulphuret of izinc^ 
Boulders. Rocks which have been transported some distance from their 
original beds; they are more or less rounded by attrition and the ac- 
tion of the weather. 
Botryoidal. Resembling in form a bunch of grapes. 
Breccia. A rock or portion of a rock composed of angular fragments 
cemented together by lime, iron, or some other substance. 
Calcareous spar^ is crystallized carbonate of lime. 
Calc sinter. A deposition of porous carbonate of lime, from the waters 
of mineral springs. 
Carbon. A simple substance, known in a pure state in the diamond only* 
It is one of the combustible elements in coaL 
Calciferous. Bearing or containing lime. 
Carbonates. Compounds formed by the union of carbonic acid and a base. 
Carbonic acid. An acid gaseous compound -composed of carbon and oxy- 
gen. It is incapable of supporting combustion, and deleterious to 
animal life. It is heavier than atmospheric air; and hence is found 
