31. "The earth's natural forces are awesome, but they are also predictable. 32. Marshall decided to use the natural force of the river to excavate and enlarge the tailrace. 33. As a result of these natural forces , the Steineberger Ley s bedrock is solid basalt. 34. His swirls and drips portray the rapid, random, and untamed effects of natural forces . 35. Puebloan tradition holds that the ancestors had achieved great spiritual power and control over natural forces . 36. They could be considered endangered because of the possibilities of erosion and other natural forces and vandalism. 37. Each surface has a polish and sheen that makes it seem untouched by human or natural forces . 38. When sediments are churned up by natural forces , the PCBs move over a much wider area. 39. Fourth-graders had to name a natural force that can alter the earth's surface. 40. Natural forces are invoked and imitated, and the viewer is artificially dwarfed by their seeming immensity.
