s--Continental base a zone of transition--Continental
base the scene of invasion and war--Peninsular extremities as areas of
isolation--Ethnic unity of peninsulas--Peninsulas as intermediaries.

CHAPTER XIII. ISLAND PEOPLES

Physical relationship between islands and peninsulas--Character of
insular flora and fauna--Paradoxical influences of island habitat on
man--Conservative and radical tendencies born of isolation and
accessibility--Islands as nurseries and disseminators of distinctive
civilizations--Limitation of small area in insular history--Sources of
ethnic stock of islands on nearest mainland. Ethnic divergence with
increased isolation--Differentiation of peoples and civilizations in
islands--Differentiation of language--Unification of race in
islands--Remoter sources of island populations--Double sources--Mixed
population of small thalassic isles--Significant location of island way
stations--Thalassic islands as goals of maritime expansion--Political
detachability of islands--Insular weakness based upon small area--Island
fragments of broken empires--Area and location as factors in political
autonomy of islands--Historical effects of island isolation in primitive
retardation--Later stimulation of development--Excessive
isolation--Protection of an island environment--Islands as places of
refuge--Islands as places of survival--Effects of small area in
islands--Economic limitations of their small area--Dense population of
islands--Geographic causes of this density--Oceanic climate as
factor--Relation of density to size--Density affected by a focal
location for trade--Overflow of island population and colonies to the
mainland--Precocious development of island agriculture--Intensive
tillage--Emigration and colonization from islands--Recent emigration
from islands--Maritime enterprise as outlet--Artificial checks to
population--Polyandry--Infanticide--Low valuation of human life.

CHAPTER XIV. PLAINS, STEPPES AND DESERTS

Relief of the sea floor--Mean elevations of the continents--Distribution
of relief--Homologous reliefs and homologous
histories--Anthropo-geography of lowlands--Extensive plains unfavorable
to early development--Conditions for fusion in plains--Retardation due
to monotonous environment--Influence of slight geographic features in
plains--Plains and political expansion--Arid plains--Nomadism--Pastoral
life--Pastoral nomads of Arctic plains--Historical importance of steppe
nomads--Mobility of p