NMBGMR Draft Geologic Data Model - v. 1.0.2
LINES: Contacts - Lithologic

revised: 08-Oct-2010

Contents:

Lith_Contacts

This feature class represents contacts between geologic units which may be either lithostratigraphic (stratiform) and lithodemic (do not conform to law of superposition). LithContacts are used to build polygons (Lith_poly) and are topologically related to these polygons. Concealed, surficial, and overlay contacts are handled elsewhere. Fault contacts that affect topology are copied here (from Fault_line) since they bound geologic units. Faults that do not completely cut polygons (dangles) are not copied to eliminate topology errors. Also, no attributes besides LineClass, Exposure, and Confidence are copied with these faults. Polygons should only be constructed from the Lith_Contacts feature class when all topology errors have been fixed. Particularly good and/or important exposures of contact relations should be recorded as point data in Feature_point and assigned a special symbol along the contact.

Field Name Field Alias Length
(text fields)		 Field Type Field Value Default Allow Nulls? Attributes / Examples Description / Notes
FGDC_code " 16 String CVD variable [null] TRUE 30.3.12 FGDC geologic symbol reference number.
LineClass LineClass 50 String CVD fixed contact FALSE see: ContactClass Basic class of contact.
IDmethod " 50 String CVD variable field evidence TRUE see: IDmethod The basis for identification of this feature.
Confidence " 16 String CVD fixed certain TRUE unspecified, certain, probable, uncertain

Confidence regarding the existence/identification and position of this feature.
Exposure " 16 String CVD fixed [null] TRUE unspecified, exposed, obscured Exposure of this feature at the surface.
CtType ContactType 50 String CVD variable [null] TRUE see: ContactType Type of basic contact (fault contacts are null because they are described in detail elsewhere).
CtGeometry ContactGeometry 50 String CVD variable [null] TRUE see: ContactGeometry Geometry of contact.
CtNature ContactNature 50 String CVD variable [null] TRUE see: ContactNature Nature of contact..
Name " 50 String variable [null] TRUE great unconformity, K-T boundary, etc Feature name (will generally be NULL)
DsplyScale DisplayScale   Long Integer CVD fixed 24000 TRUE see: DisplayScale Denominator of display scale: display feature at scales larger than number specified (=< denominator). Zero indicates data that should never be displayed.
SourceID " 128 String variable [null] TRUE "Smith, 1999a" Feature level metadata (who mapped this)
Comments " 255 String variable [null] TRUE Free text e.g. identified from detailed stereo photos Comments about this particular feature.

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Concealed_Contacts

This feature class records contacts concealed for some distance by alluvium or other cover. These lines bound subcrop polygons (Subcrop_poly) and might be combined later with other lines and with Subcrop_poly to make a derivative bedrock map.

Field Name Field Alias Length
(text fields)		 Field Type Field Value Default Allow Nulls? Attributes / Examples Description / Notes
FGDC_code " 16 String CVD variable [null] TRUE 30.3.12 FGDC geologic symbol reference number.
LineClass LineClass 24 String CVD fixed contact FALSE see: ContactClass Basic class of contact.
IDmethod " 50 String CVD variable field evidence TRUE see: IDmethod The basis for identification of this feature.
Confidence " 16 String CVD fixed certain TRUE unspecified, certain, probable, uncertain

Confidence regarding the existence/identification and position of this feature.
CtType ContactType 50 String CVD variable [null] TRUE see: ContactType Type of basic contact (fault contacts are null because they are described in detail elsewhere).
CtGeometry ContactGeometry 50 String CVD variable [null] TRUE see: ContactGeometry Geometry of contact.
CtNature ContactNature 50 String CVD variable [null] TRUE see: ContactNature Nature of contact..
Name " 50 String variable [null] TRUE great unconformity, K-T boundary, etc Feature name (will generally be NULL)
DsplyScale DisplayScale   Long Integer CVD fixed 24000 TRUE see: DisplayScale Denominator of display scale: display feature at scales larger than number specified (=< denominator). Zero indicates data that should never be displayed.
SourceID " 128 String variable [null] TRUE "Smith, 1999a" Feature level metadata (who mapped this)
Comments " 255 String variable [null] TRUE Free text Comments about this particular feature.