France. Service de la carte geologique de France Explanatory text: 6p. in MC folder. North Decimal Degree 50.9362 South Decimal Degree 50.5766 East Decimal Degree 2.7925 West Decimal Degree 1.8819 Alternate title: Saint-Omer. Relief shown by hachures. Principal meridian: Paris. Longitude is given in centesimal values (100 grades = 90 degrees) .The Service de la carte geologique de la France was integrated to the BRGM to become the only France Service geologique national.