Describe about preparation of engineering geological map in field. [2071 Bhadra][3]

The Graphical representation of purpose specific geological information or data obtained from field (after site investigation) which can be quantified (in numbers), with reference to north at certain scale is known as Engineering Geological Map.It includes lithology (distribution of rock types), soil types (alluval,colluvial,residual etc.), geomorphology (river,stream,slope aspect ,inclination,slope instabilities like mass movements i.e, landslides,debris flow,slope failure etc).

Preparations:

• All the geological features (rock units, bedding planes, faults, foliations, etc.) present in the area must be shown so that the geology of the area can eaily be underestood and interpreted.
• Rocks units or geologic strata are shown by appropriate and relevant where they exposed at the surface.
• Bedding planes and structural features such as folds, faults, foliations, and lineation are shown with the strike and dip or trend and plunge symbols which give the....

The Graphical representation of purpose specific geological information or data obtained from field (after site investigation) which can be quantified (in numbers), with reference to north at certain scale is known as Engineering Geological Map.It includes lithology (distribution of rock types), soil types (alluval,colluvial,residual etc.), geomorphology (river,stream,slope aspect ,inclination,slope instabilities like mass movements i.e, landslides,debris flow,slope failure etc).

Preparations:

• All the geological features (rock units, bedding planes, faults, foliations, etc.) present in the area must be shown so that the geology of the area can eaily be underestood and interpreted.
• Rocks units or geologic strata are shown by appropriate and relevant where they exposed at the surface.
• Bedding planes and structural features such as folds, faults, foliations, and lineation are shown with the strike and dip or trend and plunge symbols which give these features three dimensional orientations.
• Stratiographic contour lines can be used to illustrate the surface of a selected stratum illustrating the sunsurface topographic trends of the strata.
• Orinetations of planes are often measured as a strike and dip while of lines are shown as trend and plunge.Strike and dip symbols consists of a long strike line, which is perpendicular to the direction of a greatest slope along the surface of the bed, and a shorter dip line on side of the strike line where the bed is going downwards.The angle that the bed makes with the horizontal, along the dip direction, is written next to the dip line.In azimuthal system, the orientation is shown as strike / dip.

Trend and Plunge are used for linear features and theor symbol is a single arrow on the map.The arrow is oriented in the down going direction of the feature (Trend) and at the end of the arrow, the number of degrees the feature lies below the horizontal (Plunge) is noted.eg- 34/86 indicates a feature that is angled at 34 degree below the horizontal at an angle that is just East of true South.