169 
Fic. 4. Glacial boulders placed along the Brook under construction, 1912. 
‘acing north—up stream. (562). Cf. Fi 
The Southern Plain of Long Island 
South of the gravel ridge is a gently sloping plain, forming part 
of the coastal plain of eastern North America, and placed as a 
frontal apron with reference to the ridge. This plain is more or 
less dissected by valleys ten to twenty feet deep, whose streams 
(where they have not dried up) rise in the highland and flow in a 
direction a little west of south to the ocean. One of these valleys, 
about three miles east of Garden City and Mineola, 1s occupied by 
ast Meadow Brook, and another by Hempstead Brook, flowing 
through the town of Hempstead. 
It has been observed that, in places, the western slopes of these 
valleys seem to be steeper than the eastern, and the suggestion was 
made by Elias Lewis, Jr., in 1877 (Am. Jour. of Science and Arts, 
Ser. III, Vol. 13, p. 215) that this was due to the rotation of the 
earth from west to east. Owing to the inertia of the water the 
streams have tended to maintain their southern course and have 
