down-hill gradient
21Drainage system (Geomorphology) — In geomorphology, a drainage system is the pattern formed by the streams, rivers, and lakes in a particular watershed. They are governed by the topography of the land, whether a particular region is dominated by hard or soft rocks, and the… …
22sand dune — Hill, mound, or ridge of windblown sand or other loose material such as clay particles. Dunes are commonly associated with desert regions and seacoasts, and there are large areas of dunes in nonglacial parts of Antarctica. * * * Introduction any …
23Chiltern Main Line — Chiltern Railways Clubman at West Ruislip Overview Type Commuter rail, Heavy rail S …
24cell — cell1 cell like, adj. /sel/, n. 1. a small room, as in a convent or prison. 2. any of various small compartments or bounded areas forming part of a whole. 3. a small group acting as a unit within a larger organization: a local cell of the… …
25India — /in dee euh/, n. 1. Hindi, Bharat. a republic in S Asia: a union comprising 25 states and 7 union territories; formerly a British colony; gained independence Aug. 15, 1947; became a republic within the Commonwealth of Nations Jan. 26, 1950.… …
26Wind — For other uses, see Wind (disambiguation). Wind, from the …
27GEOGRAPHICAL SURVEY — Names The name Ereẓ Israel (the Land of Israel) designates the land which, according to the Bible was promised as an inheritance to the Israelite tribes. In the course of time it came to be regarded first by the Jews and then also by the… …
28Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… …
29photosynthesis — photosynthetic /foh teuh sin thet ik/, adj. photosynthetically, adv. /foh teuh sin theuh sis/, n. Biol., Biochem. (esp. in plants) the synthesis of complex organic materials, esp. carbohydrates, from carbon dioxide, water, and inorganic salts,… …
30Pakistan — /pak euh stan , pah keuh stahn /, n. 1. Islamic Republic of, a republic in S Asia, between India and Afghanistan: formerly part of British India; known as West Pakistan from 1947 71 to distinguish it from East Pakistan (now Bangladesh).… …
