Digital Data for Construction Material Sources Reported by the Arizona Department of Transportation in 1977 for Maricopa County, Arizona, USGS OFR 01-122

U.S. Geological Survey scientists desired to have the data presented in the
Source in a digital format to use in GIS and spreadsheet software programs for
aggregate models and aggregate assessment.

The data set marpits1 is an ArcInfo coverage of point features representing pit
locations and attribution data captured from an atlas of map sheets and pit
data sheets titled "A Materials Inventory of Maricopa County [Arizona]" by the
Arizona Highway Department (AHD), now named the Arizona Department of
Transportation (ADOT), hereafter referred to as the 'Source'.

Pit locations were represented by point symbols in the Source map sheets.
Points were digitized from the Source map sheets. Selected attribute data were
collected from the Source pit data and map sheets. In the Source introduction
it states:
"The pit location maps show the location of all
pits bearing Materials Services serial numbers.
Other sources are not shown. The plotted locations
are as close as possible to the true location
as the scale of the map will allow."

The point attribute data, captured from the Source pit data sheets are

"designed to show test results (sieve analysis,
plasticity index, and abrasion) for the usable
material within each ADOT pit."

The digital editor and digital compilers of the GIS data set made certain
adjustments to the data to make them complete and usable in a GIS. These
adjustments include adding points locations for records in the accompanying
Source pit data sheets where no point representation existed on the Source map
sheets, adding attribution data to the furthest extent possible for points on
the Source map sheets without entries in the accompanying Source pit data
sheets, appending a letter to the pit number of repeated (duplicate) pit
numbers to make them unique and correspond one-to-one with a record in the
Source pit data sheets, and adding a '-999' to represent 'No data' or 'No
observation' for blank entries in the pit data sheets. Table 3 in the
Open-File Report text describes the actions taken to insure data consistency
and uniqueness of the individual points. An accompanying ArcInfo arc coverage
called marbase of the generalized Maricopa County boundary, and generalized
major roadways and generalized major hydrography of Maricopa County has been
included to give a general reference of pit location in proximity to natural
and man-made features.