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u <br />TABLE OF CONTENTS <br />Paae <br />1.0 SUMMARY OF MAJOR FINDINGS ................................................................................1 <br />2.0 OVERVIEW OF FIELD GEOLOGIC STUDIES JULY 12-15, 2004 AND OF PHOTO- <br />GEOLOGIC STUDIES AUGUST 8-15, 2004 ...................................................................4 <br />3.0 INTRODUCTION .............................................................................................................5 <br />4.0 MINING MEiHOD ...........................................................................................................6 <br />5.0 GEOLOGIC FACTORS INFLUENCING SUBSIDENCE ..................................................8 <br />6.0 FIELD RECOGNRION OF SUBSIDENCE AND NON~SUBSIDENCE FEATURES IN <br />THE WEST ELK MINING AREA .....................................................................................9 <br />8.1 Subsidence Cracks and Compression Features .................................................................9 <br />6.2 Construction Cradcs..-°--° .................................•°--..........°°--------.......................--°--........10 <br />• 6.3 Desiccation Cracks .....................°-...----°°--------------°°--.............................--°----------.........10 <br />6.4 Pseudo Subsidence Cracks (Gravity-Irxluced Tension Cracks) .......................................11 <br />7.0 SUBSIDENCE PREDICTION BASED ON PAST LONGWALL MINING .......................12 <br />7.1 Vertical and Horizontal Displacement, Tiff, Curvature, and Horizontal Strain ...................12 <br />7.1.1 Maximum Vertical DisplacemeM .......................................................................13 <br />7.1.2 Ma~dmum TiR.....------•-----°-...°-°° .............................•°-----................-.................14 <br />7-1.3 Maximum Horizortal Strain ................................°----------....................-------°-.....14 <br />7.2 Maximum Projected Deptlis of Surface Cradcs ................................................................15 <br />8.0 GEOLOGIC AND TOPOGRAPHIC OBSERVATIONS IN THE SOUTH OF DMDE <br />MINING AREA ..............................................................................................................19 <br />8.1 Field Location 1 .............°°-------------.............................°--°-°------°......................---------......19 <br />8.1.1 Field Observations..-• ..............°---------..-....................--°----.................................19 <br />8-1.2 Aerial Photo Observations of Landslides North and South of Minnesota <br />Reservoir .................................................................................°---°-°--°-...............-........22 <br />8.1.3 Aerial Photo Observations of Rockfalls in the Minnesota Reservoir Area......... 25 <br />8.2 Field Location 2 ................................................................................................................. 25 <br />8.2.1 Aerial Photo Observations at Location 2 ........................................................... 28 <br />• 8.3 Aerial Photo Location 3.....-------° ...................................°-°----......................--------............29 <br /> <br />