A MAJOR LANDSLIDE ON GREERS FERRY LAKE

Early on the morning of March 28, 2005, after two days of rain, a significant landslide occurred on the north side of Stevens Point on the south shore of Greers Ferry Lake, Arkansas. The slide collided, in part, with a house crushing the garage on the south side of the house and tearing a small room off the west side.

The displaced area was over 700 feet long crown scarp to toe and 300 to 500 feet wide. The bedrock is a thick sequence of shales interrupted by thinner intervals of siltstones and sandstones in the lower Atoka Formation. The slope is compound and in profile somewhat typical slope and bench. The hillside is draped with a thin to thick soil of residuum and colluvium and was covered by a mature forest, except where disturbed by fairly recent cultural modifications. The slope averages about 20 degrees in the vicinity of the slide, but varies locally from near vertical to nearly level. The slide is divided in two major portions by a sequence of sandstones forming a significant ledge about midway down the slide area. Both the upper and lower portions of the slide are similar in that they have a steep upper section and flatten out to near level in their lower section. Rock falls, mud/debris flows, and translational and rotational slumping are all evident in various places in the slide area. Pressure ridges are common along the toes of each section. Although most of the movement on the slide occurred the morning of March 28, the slide continued to creep for several days. The main part of the slide seems to have developed on the footprint of an ancient landslide. A new road was cut into the forested hillside looping behind and up slope from the house, making a switchback to the west of the house, and passed downslope and in front of the house the previous fall.

It is likely that this road construction was the principle destabilizing influence on the slope. We noted 11 smaller landslides along a new road leading to the main slide area. We have no doubt that these other slides were the direct result of the recent road building activity and the associated clearing of the forest to either side of the roadway.