1902 Science  
The distribution of the sand is carried on from two directions: from the west along the sounth shore and from the niorth along the east and west sides of the 'forearm' of the Cape. The result is that the elbow tends to extend farther into the ocean, and Massachusetts Bay is a pocket steadily filling up with sand from the north. With the great fall of the tide on that coast, however, broad shoals are daily offered to sun and wind and the dried sands are constantly blown up on the highest dunes
more » ... the Cape, viz., those niear Barnstable. There are aneient dunes along the coast, soinetimes farther inland and even covered by forests, whose aggregation may be attrib-uted to special violence of wind action at a remote period. The most prominent results of the erosive action of the wild-driven sand are those pertaining to the general sculpture of headlands and summits of dunes, and the eating away of the softer layers of gravel and sand of which the bluffs along the east coast consist. The fine examaple of such erosion at Truro was deseribed in detail and illustrated by means of a photograph. The recessionof the face of the bluff here and everywhere from a vertical plane clearly indicates that its principal erosion is being constantly carried on by aerial rather than by marine attack. On the Cape, as elsewhere along our Atlantic coast, it is a eomniunon error to attribute the ravages on lbluffs and dunes, noticed after a severe storm, too miiuch to the incursions of the sea. A v-cry large part of the damage has been done by the violence of the wind, reinforced by vast quantities of sand and spray lifted up and hurled continuously for hours against all opposing objects. Other effects of the natural sand blast are shownv in the pitted surfaces of small bodies strewn uponi the beach, in the projecting hard minerals of the beach pebbles and in the depolishing of exposed portionis of bits of glass and pottery. 'Faceted pebbles' are lacking froum the beaches, because there is too much motion to permit of grinding anything to a fiat surface. The rapidity of the eroding action under favorable eireunistances is surprising. During the great gale of November 25, [N. S. VOL. XV. No. 366. 1899, one night sufficed to convert into groundglass the window panes in the exposed sides of the life-saving station at Truro. No scratches or grooves appear in these surfaces, such as have been observed in the sand-fretted pebbles of a desert, the conditions of sand erosion on a beach tending to pit the surface rather than to producee striae- The least obvious, bnt perhaps the most important, effect of this form of erosion is uponi the flying sand grains themiselves by nmutual attrition, minute particles not being protected from wear as they are when suspended in water. By the splitting of particles fromn the grains and their own final reduction to the most minute size, the production of silt is constantly in progress upon these windy beaches, (and it is regularly carried awav in suspension by every tide. The papers of the evening were discussed by Professors
doi:10.1126/science.15.366.28 fatcat:7ghmr4prgrgfrgzfkt65zauure