Lead-rich sediments, Coeur d'Alene River valley, Idaho; Area, volume, tonnage, and lead content: River reach data (by segment)

This metadata file (pbrchseg.met) describes three shape files used.
Shape file rivreach.shp contains the upstream and downstream
boundaries of seven reaches of the river. Natural features define
river-reach boundaries at the confluence of the North and South
forks of the Coeur d'Alene (CdA) River, the transition from a
gravel- to a sand- bottomed channel, the mouth of the river, and
the base of the delta front. Other river-reach boundaries are at
midpoints between river-channel drill transects. River-reach
boundaries provide end limits for Estimation Units, for which
thickness, volume, tonnage, and lead content of Pb-rich sediment
were estimated.
Shape file segments.shp contains up- and down-valley boundaries
of 3 sections of the CdA River valley (upper, middle, and lower),
each subdivided into three segments (a, b, and c). We defined these
valley sections and segments to facilitate definition and description
of along-valley differences in the character of deposits of metal-
enriched sediment. These boundaries also define east- and west-end
limits of Estimation Units, for which thickness, volume, tonnage,
and lead content of Pb-rich sediment were estimated.
Shape file Pb1000.shp outlines the area within which samples of
surface sediment contain at least 1,000 parts per million (ppm).
This outline is the 1,000 ppm Pb contour, which defines the
geochemical limit (or cutoff concentration for Pb) of Estimation
Units, for which thickness, volume, tonnage, and lead content of
Pb-rich floodplain sediment were estimated.