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spring of 1983. Any construction of surface facilities <br />within these slopes would be very difficult. <br />o Several landslides, at least one of them of a <br />considerable size, have been identified in the immediate <br />vicinity of the entry to the abandoned Farmers Mine. The <br />largest of these landslides is located immediately south of <br />the entry, above the old mine bench. Smaller slides appear <br />to cover the mine entry. According to the limited data <br />available on mining activity in the area (J. V. Roberts, oral <br />communication), the mine entry and the surface facilities <br />were established in either an old landslide or in an <br />unstable slope. Mining or surface activities possibly <br />contributed to further sliding or the development of new <br />landslides, although the slope is thought to have been <br />unstable prior to mining. There is no direct proof that <br />sliding on this site is related to failures of outcrop <br />barrier pillars. <br />2.5 SUBSIDENCE <br />A field inspection of the subsidence cracks previously <br />identified by CWI was made during early June, I98:. The <br />location and orientation of the cracks were surveyed earlier <br />• by CWI. As described in other parts of this report, the <br />cracks are located approximately above a thin pillar <br />separating the 1st and 2nd West panels. <br />They are identifiable on several ridges and depressions <br />northwest of the Orchard Valley Mine portals. The cracks <br />have a direction approximately east-west, with most of them <br />striking N6014. The cracks are more visible at the ridges <br />than in the depressions; a maximum opening of up to 18- <br />inches was measured on some of them. hlost cracks appear to <br />have a fresh character, with little or no sloughing, except <br />for minor :.racks where the thin topsoil cover fills the <br />crack. <br />All inspected cracks were developed in colluvial soils. <br />The ridges and depressions in the vicinity are covered by <br />thick deposits of colluvial soils containing a high <br />percentage of basaltic boulders. The widest cracks enabled <br />inspection the soil to a depth of some 20 - 25 feet; bedrock <br />could not be identified in either of them. <br />A graben-like structure could be found between two <br />cracks that are some 20 feet apart; the block betweer. these <br />two fracture dropped apparently by some 12 - 1F inches. <br />• - 11 - <br />