UpDate - Vol. 13, No. 25, Page 3
March 24, 1994
New editions available; Geological Survey puts First State on map

     Delaware is again living up to its reputation as the First State. In
this case, it is the first state to be totally remapped in a new edition of
7.5 minute, 1:24,000 scale, topographic maps through a joint project of the
Delaware Geological Survey (DGS) with the U.S. Geological Survey (USGS)
supported by the General Assembly.
     According to William S. Schenck, associate scientist with the Delaware
Geological Survey (DGS) and coordinator of its Cartographic Information
Center (DGSCIC), there are 57 topographic quadrangle maps of the state that
provide vital, detailed information. Mini-encyclopedias, the maps show
elevations, water, roads, communities, landmarks, forests, coastal regions
and population density.
     Using aerial photography, conventional surveying and satellite
surveying techniques, the project has taken five years to complete. Since
the last editions of maps were available, advanced computer capabilities
have allowed for the shaped of the earth, the location of its center and
sea level to be more clearly defined.
     The resulting, more accurate maps reflect these advances in Delaware,
according to Schenck, who has been working on the project.
     The maps are so detailed that, in less populated areas, each house is
shown as well as outbuildings. Swamps, marshes, forested areas, coastal
areas and elevations are all indicated, and most roads and developments are
labeled, along with other information such as whether a development is a
mobile home community or not.
     Topographic maps illustrate the elevation of the land surface above
mean sea level. The high point of Delaware is on Ebright Road, near Concord
High School in northern Delaware. The low point is in some sand and gravel
pits in southern Delaware which are below sea level, Schenck said.
     Every federal, state, county and municipal agency relies on the maps
for environmental and engineering projects or in emergency situations. "In
the event of coastal flooding, for example, the Delaware Emergency
Management Agency (DEMA) may decide that residents in mobile homes should
be evacuated first because they are more vulnerable than traditional
houses. Or, if a hazardous substance is spilled from a truck, rescue
workers have to be able to pinpoint the location and have environmental
information about the area," Schenck pointed out.
     Most of the new quadrangle maps of Delaware have been printed and are
available to the public at nominal cost. The center also can order all
types of maps and publications offered by the U.S. Geological Survey as
well as providing access to DGS publications concerning the geology of
Delaware.
     Another service offered by DGSCIC is a cartographic data base
containing a statewide inventory of maps, charts and aerial photographs of
Delaware. A search of this data base will provide a listing that tells
where they are located throughout the state in such sites as libraries,
historical societies or government agencies.
     A Delaware graduate, Schenck is a geologist currently working on his
master's degree here. In addition to his cartographic work, he studies the
geology of the state. Part of northern Delaware is in the Appalachian
Piedmont Province with crystalline rock formations, while the rest of the
state is part of the Atlantic Coastal Plain characterized by unconsolidated
rock. The dividing line is roughly the Kirkwood Highway, he said.
     An example of one type of rock found in the state is the huge boulder
in the lobby of the DGS building on campus, located off Academy Street. The
"DGS pet rock," as it is known, was placed there by crane after the
foundation was poured with the structure of the building going up around it
later.
     In another area, the DGSCIC monitors 460 Delaware benchmarks. These
concrete markers with metal disks, whose tops are mostly set flush with the
ground, have information about the elevation of various points of the
terrain.
     DGSCIC also aids the Delaware State Boundary Commission in maintaining
the monuments marking Delaware's borders. Some of these were the original
markers placed by Mason and Dixon in 1765; others are more recent. One of
the markers is in the middle of Elkton Road, only it cannot be seen since
it was placed in a specially constructed manhole when the state of Maryland
wanted to install a left-hand turn lane, Schenck said.
     Schenck visits schools and gives talks on geology and cartography.
Frequently, school children visit the DGS building where he gives them a
tour of the geological exhibits and displays.
     For the convenience of Delawareans, the center offers Delaware
quadrangle maps for sale at a cost of $2.50 each. They may be purchased on
site or by sending a check to DGS Cartographic Information Center, Delaware
Geological Survey Building, University of Delaware, Newark DE 17916. For
further information, call 831-8262.
                                                  -Sue Swyers Moncure