24. Diagrams to illustrate the shapes of rock folds 44 25. Secondary and tertiary flexures superimposed upon the primary ones 44 26. A bent stratum to illustrate tension and compression upon opposite sides 45 27. A geological section with truncated arches restored 47 28. Diagram to illustrate the nature of strike and dip 47 29. Diagram to show the use of T symbols for strike and dip observation 48 30. Diagram to show how the thickness of a formation is determined 49 31. A plunging anticline 50 32. A plunging syncline 50 33. An unconformity upon the coast of California 51 34. Series of diagrams to illustrate the episodes involved in the production of an angular unconformity 52 35. Types of deceptive or erosional unconformities 53 36. A set of master joints in shale 55 37. Diagram to show the manner of replacement of one set of joints by another 56 38. Diagram to show the different combinations of joint series 56 39. View of the shore in West Greenland 57 40. View in Iceland which shows joint intervals of more than one order 57 41. Faulted blocks of basalt near Woodbury, Connecticut 58 42. A fault in previously disturbed strata 59 43. Diagram to show the effect of erosion upon a fault 60 44. A fault plane exhibiting drag 60 45. Map to show how a fault may be indicated by abrupt changes in strike and dip 61 46. A series of parallel faults revealed by offsets 61 47. Field map prepared from the laboratory table 64 48. Areal geological map based upon the field map 64 49. A portion of the ruins of Messina 67 50. Ruins of the Carnegie Palace of Peace at Cartaga, Costa Rica 68 51. Overturned bowlders from Assam earthquake of 1897 69 52. Post sunk into ground during Charleston earthquake 69 53. Map showing localities where shocks have been reported at sea off Cape Mendocino, California 70 54. Effect of seismic water wave in Japan 70 55. A fault of vertical displacement 71