22 REPORT OF NATIONAL MUSEUM, 1889 



Among these, which may perhaps be properly grouped under the 

 head of constructive and reproductive effects of water, need at present 

 be mentioned the exceptionally fine series of stalactites aud stalagmites, 

 mainly from the Luray Caves of Virginia; the beautiful siliceous and 

 calcareous sinters from the geysers and hot springs of the Yellowstone 

 Park and the peculiar imitative calcareous tufas from Lake Lahoutou, 

 Nevada, as collected aud described by Mr. I. C. Russell, of the U. S. Geo- 

 logical Survey. Besides these are many specimens less conspicuous for 

 their size, but none the less instructive. Among them attention may be 

 directed to the agates which were deposited from solution in the cav- 

 ities of trap rocks. In the specimen from near South Boulder Creek, 

 Montana, is shown a small agate still in the cavity which it formed. 

 Other solution products are the rock salts from New Iberia, Louisiana 

 (38461); Stassfurth, Germany, and the calc tufas coating leaves and 

 stems of plants from Soda Springs, Idaho (39130). 



This series is supplemented by photographs of the tufa deposits 

 about Mono Lake, California, and the geyser and hot spring deposits 

 in the Yellowstone National Park. 



Running streams carrying fine detritus act in a mechanical as well as 

 chemical manner. In this way are formed such curiously eroded forms 

 as the granite bowlder from Craftsbury, Vermont, in which the finer 

 grained portion has shown greater resistance than the upper coarser 

 part (70099). Objects of this nature are as a rule too large for exhibi- 

 tion as specimens, and recourse must be had to models and illustrations. 

 Here, then, attention may be directed to the large model of the Grand 

 Canon of the Colorado River, and also the ten panoramic views of the 

 same placed high against the north wall of the range, as well as the 

 transparencies in the windows on the south side. 



The transporting aud constructive power of running streams is at 

 present indicated in the series only by a few vials showing the amount 

 of mineral and organic matter contained in a litre of Potomac water 

 during a season freshet. This part of the exhibit has not yet been 

 worked out in detail. The transporting power of ocean currents is 

 shown by a small collection of seeds cast up on the beach at Palisadoes 

 Plantation, island of Jamaica, a part of which are quite foreign to the 

 island, aud by fragments of pumice from the volcano of Krakatoa, but 

 which were found floating on the surface of the water at a distance of 

 1,315 miles from their source. There is need of more material here. 



The mechanical action of waves as displayed in the undermining aud 

 breaking down of rocky cliffs can be shown only by models and illus- 

 trations. A small amount of space is, however, here given to a series 

 illustrating the resultant product of such action. 



The material selected comes from Cape Elizabeth, on the coast of 

 Maine. The cliffs on the shore are composed of finely fissile schists 

 which are traversed by numerous veins of quartz. The continual ham- 

 mering of the waves from the open Atlantic causes the schist to slowly 



