Plant succession on non-calcareous screes (talus slopes) is initiated in 2 types of sites: (1) at points along the top margin of the slope where debris is forming most slowly, and (2) in small areas just below large pleces of rock which are imbedded so deeply in the scree as to be comparatively stable. The typlcal successional stages are (a) bryophyte cushion (lichens grow too slowly to be important ploneers in such an unstable substratum), (b) Cryptogramme crispa, (c) Calluna heath, and (d) Quercus sessiliflora climax. This series begins in restricted and protected areas, but as the succession progresses the vegetation spreads in a downward direction and forms elongate colonized strips down the scree. Ancient screes are completely covered with oaks. The low altitude of these screes, mostly below 762 m., almost precludes the characteristic alplne scree plants.