Name: GRAV_STN
Description: GRAVITY STATIONS
Feature type: POINT
No. of features: 11283

Items:      Item Descriptions:
AREA        Holds the area of a polygon. The value is 0 for points	
PERIMETER   Holds the perimeter of a polygon. The value is 0 for points	
GRAV_STN#   Internal sequence number (software assigned)	
GRAV_STN-ID A feature id generated automatically (user assigned)	
LONG        Longitude of station	
LAT         Latitude of station
VALUE       Pixel value in GRAV_L image (represents a range of gravity values)
COUNT       Number of pixels that share the same VALUE
MIN         Minimum gravity value (mGal) for class represented by pixel value	
MAX         Maximum gravity value (mGal) for class represented by pixel value

Item Domains
Item:       Item values:
LONG        >10 unique values

LAT         48.96 to 60.00

VALUE       1 to 254

COUNT       2248 to 3191	

MIN         -88.52 to -6.41
	
MAX         -80.01 to 7.59

Sample Record:
AREA         =  0.000
PERIMETER    =  0.000
GRAV_STN#    =  2
GRAV_STN-ID  =  29702
LONG         = -95.47000
LAT          =  59.99500
VALUE        =  84
COUNT        =  2756
MIN          = -50.2700
MAX          = -50.1200

Processing:

Latitude and longitude coordinates were provided by the Geophysical Data 
Centre(GSC).  Points represent locations where gravity measurements were
taken.  These points were projected to UTM and an overlay of the points 
and the Bouguer Gravity image was made.  The result is a table that 
quantifies the relationship between the pixel value in the image provided
on the CD and the original Bouguer Gravity image (mGal). 

The Bouguer Gravity image depicts Bouguer gravity anomalies, based on 
data from the holdings  of the Canadian Geodetic Information System 
maintained by the Geodetic Survey Division, Geomatics Canada.  
 
Variations in the Bouguer gravity anomaly field reflect lateral variations
in the density of the underlying rock units.   The interpretation of 
gravity data has  applications in geological mapping, basin analysis, and
in mineral, oil and gas exploration by providing constraints on the 
subsurface.  Gravity data are also used in the computation of the geoid. 

All measurements used in this compilation were reduced to the International
Gravity Standardization Net 1971 (IGSN71) datum.  Theoretical gravity
values were calculated using the Geodetic Reference System 1967 (GRS67) 
gravity formula.  The Bouguer correction used a vertical gravity gradient
of 0.3086 mGal m-1 and a crustal density of 2670 kg m-3.   The data spacing
for the given area  ranges from 3 km to 12 km. 
 
Source:

Digital data in point or grid form, as well as hardcopy plots, are available 
from the Geophysical Data Centre:

Geological Survey of Canada, 
Room 235, 615 Booth Street, 
Ottawa, K1A 0E9. 
Tel:(613)995-5326
FAX:(613)952-8987.  
Email: infogdc@agg.NRCan.gc.ca 
WWW: http://gdcinfo.agg.NRCan.gc.ca

File Locations