Directionally drilled horizontal boreholes drilled in advance of mining can provide valuable information about the area to be mined along its length that cannot be determined by the limited sampling area of vertical boreholes.
 

This includes geological information such as seam thickening or thinning, faults, local dips, or other anomalies such as burn areas, high water or gas content areas, etc.  
 

Controlled borehole deviations (“laterals” to the sides or “sidetracks” up or down) can be drilled to further probe or define areas of interest where more information is desired or critical.