Ž . Catena 33 1998 241–254 Edaphic interslope and valley bottom differences at ‘‘Evolution Canyon’’, Lower Nahal Oren, Mount Carmel, Israel E. Nevo a, ) , A.P. Travleev b , N.A. Belova b , A. Tsatskin c , T. Pavlıcek a , A.F. Kulik b , N.N. Tsvetkova b , D.C. Yemshanov b ´ˇ a Institute of EÕolution, UniÕersity of Haifa, Mount Carmel, Haifa 31905, Israel b Department of Geobotany, Soil Science and Ecology, DniepropetroÕsk State UniÕersity, TitoÕa Str. 2 r 7, DniepropetroÕsk 59, Ukraine c Institute of Archaeology, UniÕersity of Haifa, Mount Carmel, Haifa 31905, Israel Received 30 September 1997; revised 26 May 1998; accepted 27 May 1998 Abstract The opposite slopes of lower Nahal Oren, Mount Carmel, Israel, designated ‘‘Evolution Canyon’’, display physical and biotic contrasts, although both are cut in Upper Cenomanian calcareous limestone. The three-fold greater solar radiation makes the south-facing slope warmer, drier and more variable than the north-facing slope and valley bottom. Consequently, biodiversity Ž . is greater. Microclimate mesic–xeric is a major force driving adaptive evolution, and causing soil divergence. The soils on both slopes are Terra Rossas in the Israeli classification system Ž . Ž Rhodoxeralfs in US taxonomy . However, selected properties pH, humus content, NH –N 4 . content, cation exchange capacity and others display greater interslope than intraslope differ- ences. The north-facing Terra Rossas have a dark-coloured A1 humic horizon, which is better developed than in south-facing Terra Rossas. Differences in soil morphology, moisture regime and microfabric between the north- and south-facing soils suggest that they belong to different taxonomic classes. These differences probably result in part from the forested ecosystem of the north-facing slope versus the savanna-like ecosystem of the opposite slope. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Terra Rossa; Microclimate differentiation; Slope–soil differentiation; Biotic divergence; Mount Carmel; Israel ) Corresponding author. Fax: q972-4-8246554; E-mail: rabi301@haifauvm 0341-8162r98r$ - see front matter q 1998 Elsevier Science B.V. All rights reserved. Ž . PII: S0341-8162 98 00071-X