51 50. TimberlineAltitude beyond which trees do not grow.
52 51. ForestThe dense growth of trees covering a large area.
53 52. QuarryAn open excavation from which stone is taken.
54 53. Sink HoleA natural depression on the earth’s surface showing that there is an open area underground which is sinking.
55 54. SedimentMaterial that sinks to the bottom of a liquid.
56 55. Flood PlainA plain along a river; formed by sediment from floods.
57 56. Alluvial FanSloping where a stream slows down, into a level plain.
58 57. LongitudeImaginary lines that run through both poles (N/S). The central line of longitude is called the Prime Meridian and it runs through the Royal Observatory in Greenwich, England. Lines tell us how far east and west we are from the PM.
59 58. LatitudeImaginary lines which tell us how far north or south one is from the Equator; the imaginary line exactly ½ way between N and S poles.
60 59. Prime MeridianCentral line of longitude that runs through N and S poles; Greenwich, England.