This paper treats of the topographical and geological groundwork for the sustainable development of the northwestern slope of diminishing gradient of Mt. Noro in the Gohara area of the northern part of Kure City，Hiroshima Prefecture in western Japan. This slope which has been well known among many geographers and geologists of Japan is covered with the deposits composed of talus，block field or Felsenmeer，block stream and mud flow or debris flow. This slope is planned to be the housing site，some part of which has already been developed and is called Green Town Gohara，and all of the northwestern slope of diminishing gradient of Mt. Noro in Gohara will be developed in near future. The boulders of block field or Felsenmeer formed by the frost shattering in the late Pleistocene time are lying on the talus deposits in 250 to 300 m in sea level. The block field and the mud flow or debris flow formed in the late Pleistocene to the Holocene are distributed over the slope-area of Gohara of 200 to 250 m in sea level. In the middle of Green Town Gohara giving a trend of northwest to southeast，we presume that there can be a current of underground water there and this is to be a buried stream covered with the talus deposits and the debris flow.