This paper discusses the preliminary investigation of a proposed dam along Mayo Ine River in  Mayo-Ine- Ngurore, Northeastern Nigeria. The objectives are to  ascertain the competency  or  otherwise  of  the  rocks  and  soils  of  the  area, determine  depth  to  rock  level and  to  suggest  appropriate  tr eatment  necessary  if  need  be.  The  method  used  was
Electrical  resistivity  survey ,  and  was  carried  out  before  drilling;  this  was  to  narrow down  the  number  of  drill  holes and  also  to  cut  cost  of  foundation  investigation.  It involved marking out 3nos profiles at 100m intervals along the likelihood areas to be dam  axes,  as  centerline,  upstream  and  downstream  lines;  and  run  24nos  vertical electrical  sounding  (VES)  using  Schlumberger  array  on  them.  Of  the 24nos VES locations, 16 have 3nos layers  (sandy-silty  clay;  gravelly-  sandy-  silty  clay;  and basement rocks), while the remaining have weathered rocks overlying the basement as the 4^th layer .  The method revealed  that  the  depth to basement  at  the  river  channel  was about 18m.This  is  close  to  22.2m  obtained  during  the  geotechnical  investigation  that  followed the  geophysical  method. It  was then  concluded  that  few  numbers  of  test  holes  be  drilled along  these  profiles  to  correlate  the  inferr ed  depths  and  lithologies.

KEYWORDS:  Basement rocks, Geophysical sounding, Schlumberger array, Lithology, alluvial