ty have been computed partly from sample analyses and measurements and partly from reasonable geologic projections. The points of observation are ½ to 1 ½ miles apart. Indicated coal is projected to extend as an ½ mile wide belt that lies more than ¼ mile from the outcrop or points of observation or measurement.Inferred coal resources�C Coal in unexplored extensions of the demonstrated resources for which estimates of the quality and size are based on geologic evidence and projection. Quantitative estimates are based largely on broad knowledge of the geologic character of the deposit and for which there are few, if any, samples or measurements. The estimates are based on an assumed continuity or repletion of which there is geologic evidence; this evidence may include comparison with deposits of similar type. Bodies that are completely concealed may be included if there is specific geologic evidence of their presence. The points of observation are 1 ½ to 6 miles apart.
In situ- In the natural or original position. Applied to a rock, soil, or fossil when occurring in the situation in which it was originally formed or deposited.
Intake- The passage through which fresh air is drawn or forced into a mine or to a section of a mine.
Intermediate section- A term used in belt and chain conveyor network to designate a section of the conveyor frame occupying a position between the head and foot sections.
Immediate roof- The roof strata immediately above the coalbed, requiring support during the excavation of coal.
Isopach- A line, on a map, drawn through points of equal thickness of a designated unit. Synonym for isopachous line; isopachyte.
J
Jackleg- A percussion drill used for drifting or stopping that is mounted on a telescopic leg which has an extension of about
2.5 m
. The leg and machine are hinged so that the drill need not be in the same direction as the leg.
Jackrock�C A caltrop or other object manufactured with one or more rounded or sharpened points, which when placed or thrown present at least one point at such an angle that it is peculiar to and designed for use in puncturing or damaging vehicle tires. Jackrocks are commonly used during labor disputes.
Job Safety Analysis (J.S.A.)- A job breakdown that gives a safe, efficient job procedure.
Joint- A divisional plane or surface that divides a rock and along which there has been no visible movement parallel to the plane or surface.
K
Kettle bottom- A smooth, rounded piece of rock, cylindric
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