Show Ji F f 0 AN N AMERICAN BLUE GROTTO OC A Beautiful Cavern Located Lk wk l Many of the beautiful phenomena seen at the celebrated blue grotto of the Island of Capri are reproduced on ona ona a small scale in a cavern at Lake Minnewaska Minnewaska Min Min- New York says Science This lake is situated on the Shaw- Shaw range of mountains at an elevation elevation elevation ele ele- of about 1700 feet It lies in a basin excavated in glacial times about half halt a mile long and less than a quarter quarter quarter ter In width and of depth reaching seventy feet The rock on all sides Is a white quartzite known as Shaw- Shaw grit which rests upon shale but no outcrop of the latter is visible at the lake The quartzite Is compact to granular and contains in places pebbles of white quartz It Is very free from admixture so that it yields to the water very little soluble matter Bare cliffs rising to the height of feet bound the east side of the lake while the v v. stern banks are well wooded The cliffs are vertical and fringed at their base by the usual talus which however Is made up oi el blocks of unusual size The cavern Is formed by several huge rocks overhanging overhanging overhanging over over- hanging the water so as to form a comparatively dark hole and the space between the under side of the sloping rocks and the water varies from about two feet to not more than two Inches The cavern faces the southwest it is Is very irregular in shape and at one point the roof and walls reverberate In response to a deep bass note The water just at the entrance of the c cavern vern v- v ern em Is three thirty-three feet deep and two or three feet away forty feet it Is very transparent at considerable depths As the rocks overhanging so close to the water the optical effects can only be seen by a swimmer and It was while swimming along the shore that I discovered the American blue grotto three thre years ago As one approaches approaches ap ap- proa hes the mouth of the cavern the bluish color of the water is noticeable noticeable noticeable notice notice- able but the beautiful effects are best seen by entering the opening and and lookIng looking looking look- look Ing outward toward the light The water varies In color from Nile green I through turquoise blue and sky blue I to deep indigo blue and in all these I shades exhibits the silvery appearance I when agitated characteristic of the grotto of Capri A body immersed in inthe inthe inthe the water has a beautiful silvery sheen similar to the reflection o of oZ moonlight The water has these colors at all aU hours but they are strongest when the sun is In the zenith late in the afternoon afternoon afternoon after after- noon the slanting rays of the sun enter the opening and light up the cavern greatly diminishing the optical effects The water retains retains' the characteristic color but without the silvery sheen on cloudy days and even during rain but especially strong when fleecy white clouds bar direct sunlight The relation relation relation rela rela- tion between the different hues green and blue to the aspect of the sky whether clear or overcast is n not t evi evi- dent Another pleasing phenomenon must be mentioned Just below the water line where the rocky sides are lapped by the waves the white quartzite quartz- quartz ite He exhibits a brilliant green hue this bright color is limited to a space about three or four Inches below the level of the lake and to certain walls of the cavern The bare arm immersed In the water partakes of the green color when the light is reflected at one angle and of the silvery blue color at another angle The interior size of the cavern is not easily given but the face of the overhanging rocks measures about forty feet and it is surprising that so small a cavern can produce such a variety of fine effects |