grcwth of red-berried elder (Sambucus racemosa) t the 
latter disappearing or becoming less frequent in the 
denser shade of the mesophytic forest further down the 
slope. Along the upper limit of the maple forest, it 
is not uncommon to see the flat, upturned root systems 
of trees, especially maples, which have adapted themselves 
to a layer of soil not over 1 dm. thick over the rock 
surface. This area is more or less subject to windfalls, 
apparently not because the velocity of the wind is greater 
here than nearer the summit, but because it forms a 
critical line between the low types of trees which spread 
their roots out through the shallow soil, with crevice 
connections in many oases, and the taller types which owe 
their increased size to a deeper, richer soil, but which 
offer a greater leverage to the force of the wind. 
The above description of the transition from 
rocky summit to mesophytic forest applies in general to 
the higher portions of the range. Variations naturally 
occur, depdnding op the elevation, exposure, local topo¬ 
graphy and depth of soil. 
(2) The escarpment and its associations. 
The height of the rock face or escarp¬ 
ment varies at different points along the range, as shown 
in fig. 24. The upper portion may be vertical or nearly 
