Fill in the response. Dialog:
  Person 1) What is the difference between the topography of the north and south sides of Nimbus Dam?;
  Person 2) Along the north side, the higher elevations consist of the resistant material (bedrock) that composes the bluffs and slopes along the American River, while on the south side the lower relief is the result of a combination of low topographic, erodible material located within the floodplain of the American River, and of areas of man-made embankment fills above natural grade.;
  Person 1) Is there anything else interesting about the topography of Nimbus Dam?;
  Person 2) The Nimbus Powerplant is located on the north side of the American River and on the left side of Nimbus Dam via looking east.;
  Person 1) What is the function of the Nimbus Powerplant?;
  Person 2) 
The powerplant provides backup to the main powerplant that is located upstream at Folsom Dam.