Some Engineering Problems Of The Panama Canal In Their Relation To Geology And Topography

ILLUSTRATIONS. Page. Plate I. Hill type of topography, looking southward and eastward from Zion (Reservoir) Hill, Culebra................................................ 10 II. Hill type of topography, looking northward and eastward from Zion Hill, Culebra....!................................................. 10 III. Coastal-plain type of topography...................................... 12 IV. Generalized geologic map of the Canal Zone............................ 12 V. Las Cascadas agglomerate.............................................. 20 VI. Bedding of upper part of Culebra formation............................ 22 VII. Dikes in Cucuracha formation.......................................... 22 VIII. Emperador limestone beds, near Las Cascadas, showing fault...... 24 IX. Ancon quarry, on the southwest end of Ancon Hill...................... 28 X. Basaltic columns exposed in Culebra Cut near Cucuracha elide.... 30 XI. A, Columnar jo’nting or shrinkage cracks in basalt, Malonis Island; 8, Horizontal jointing or shrinkage in basalt, Malonis Island. 34 XII. Culebra Cut in the making.............................................. 48 XIII. Culebra Cut completed and water in.................................... 48 XIV. Bulging of rocks in bottom of Culebra Cut, Culebra.................... 52 XV. Map and sections to show geologic conditions and probable limits of sliding ground, Culebra and vicinity.............................. 56 XVI. Fault zone near Culebra............................................... 58 XVII. Terracing on both sides of Culebra Cut to relieve strained conditions of slopes............................................................... 58 XVIII. Terracing to relieve strained conditions of slopes, east side of Culebra Cut...................................................................... 58 XIX. Fault plane at Contractors Hill........................................ 58 XX. Fault plane at Gold Hill................................................ 60 XXI. Slide nearly opposite Las Cascadas..................................... GO XXII. Slide near Cucuracha. village, east side of Culebra Cut................ 62 XXIII. Cucuracha slide, looking north from west bank, south of Contractors Hill..................................................................... 62 XXIV. Dredges working on Cucuracha slide after the water had been turned into Culebra Cut.................................................... 62 XXV. Fault or break in rocks on west side of Culebra Cut near sta tion 1652. 62 XXVI. Slide on east side of Culebra Cut near station 1652........ 64 XXVII. La Pita slide.............................................. 64 XXVIII. Columnar structure in hardened flows of mud-lava............ 66 XXIX. Slide near the division office, Empire..............*.................. 66 Figure 1. Generalized geologic section across the Isthmus.......................... 17 2. Rock succession in the Canal Zone...................................... 18 3. Cross section of Culebra Cut through Cucuracha slide.................... 23 4. Cross section of Culebra Cut at station 1782............................ 23 5. Cross section of Gatun Dam, showing dry fill and hydraulic fill... 42 6. Diagram showing resultants of deformative pressures..................... 49 7. Ideal cross section to illustrate excavation deformations....... 50 8. Ideal cross section to illustrate canalward deformation movements.. 51 9. Cross section of slide shown in Plate XXII.............................. 61 6 .