. Scientific survey of Porto Rico and the Virgin Islands. Scientific expeditions. HODGE, GEOLOGY OF THE COAMO-GUAYAMA DISTRICT 157 of the Salinas Eiver. Salinas Hill^ the eastern extremity of the Cerro Raspado, rises to four hundred feet, and from this place the elevation increases till just east of Coamo Springs, where the elevation of the Cerro l^imentol is one thousand feet. Just west of Coamo Springs the elevation is again onl}^ six hundred feet, but it rises westward to over one thousand /tVo xJueyes Wafer Gap. Coamo Wafer Gap. tSqlinas Hitl. /\<^uirre HiUs I Sa/ina'S Wind Gap,. Fig. 1
. Scientific survey of Porto Rico and the Virgin Islands. Scientific expeditions. HODGE, GEOLOGY OF THE COAMO-GUAYAMA DISTRICT 157 of the Salinas Eiver. Salinas Hill^ the eastern extremity of the Cerro Raspado, rises to four hundred feet, and from this place the elevation increases till just east of Coamo Springs, where the elevation of the Cerro l^imentol is one thousand feet. Just west of Coamo Springs the elevation is again onl}^ six hundred feet, but it rises westward to over one thousand /tVo xJueyes Wafer Gap. Coamo Wafer Gap. tSqlinas Hitl. /\<^uirre HiUs I Sa/ina'S Wind Gap,. Fig. 17.—Coamo Springs Range The sky-line is formed by the crest of the Coamo Springs Range. The middle portion of the sketch is occupied by the present coastal plain. feet at Jacaquas Eeservoir. To the north a great subsequent lowland has been carved, and to the south and east of the Coamo Eiver the coastal terraces, carved in a later formation, reach to the foot of these mountains. AVind-gaps in its crest are common. In places the crest is double and in others triple, due to the intercalated and easily eroded beds of tuff. GENESIS Specimens selected either at random or by intent from various portions of the limestone formation universally show algal structure. In some parts, where only little shreds and fragments are to be found, the former presence of alga? is attested to by the faint outlines of their former thalli preserved in the recrystallized calcite. From top to bottom and through- out the entire length the formation was originally composed of about 40 per cent algas—an estimation based upon the percentage found in the many thin sections studied. In some of the thin sections and hand speci- mens the ramifying branches of the former plants can still be seen, but for the most part the algas are in fragments. The fragments are more or less rounded and, of course, this rounding is largely the result of surf- work, but in part it undoubtedly was due to terrestrial agencies—
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscienti, bookyear1919
