18i 



SCIENCE. 



[N. S. Vol. XIV. No. 344. 



SHOBTEB ARTICLES. 



THE ORIGIN OF TRAVERTINE FALLS AND 

 REEFS. 



In a recently published article, Professor 

 Davis, ia speaking of certain travertine cas- 

 cades and reefs, says : " We could not find any 

 satisfactory explanation for the growth of these 

 travertine reefs," - and he refers to an occur- 

 rence of falls over travertine reefs in Central 

 America as if such deposits were unusual. 



In the limestone regions of East Tennessee 

 travertine cascades are common. A creek that 

 enters the Frenchbroad river a mile and a half 

 above Dandridge, Jefferson county, has a series 

 of travertine falls where the stream emerges from 

 the hills upon the bottom lands of the river. 

 The narrow valley of the stream is in places 

 completely floored over with travertine. Simi- 

 lar deposits occur in the town of Dandridge, 

 especially near the ferry over the Frenchbroad, 

 where a small stream pitches over the edge of 

 the bluflf. At many of the falls the deposit has 

 grown outward until the water pours over bel- 

 lied protrusions of the travertine. It is worthy 

 of note in that particular region that springs 

 whose waters are equally charged with lime 

 deposit no travertine where they flow quietly 

 into the river. 



In the vicinity of Stanford University, Cali- 

 fornia, some of the streams descending from the 

 calcareous areas of the Coast Range are heavily 

 charged with lime and deposit travertine wher- 

 ever the waters are thrown into spray. Like 

 most mountain streams they descend by a series 

 of terraces, or steps, represented by quiet 

 stretches having little cascades at theirup-stream 

 and down-stream ends. These cascades are made 

 of rocks, frequently water-worn boulders, and 

 in every instance the boulders at the cascades 

 are covered with more or less travertine, while 

 similar boulders along the quiet stretches and 

 especially in the deeper waters are without the 

 travertine. 



The waters of Congress Springs, in Santa 

 Clara County, California, are highly charged 

 with carbon dioxide and carry much lime in 



* ' An Excursion into Bosnia, Hercegovina and 

 Dalmatia,' by W. M. Davis, Geological Society, 

 Phila., III., 42-44. 



solution. The water is now conducted through 

 open wooden troughs to storage tanks, and 

 wherever the troughs are so steep that the 

 water is rippled the travertine is rapidly de- 

 posited and has to be removed from time to 

 time in order to prevent the complete filling up 

 of the troughs. The old stream bed along 

 which this Congress Spring water formerly ran 

 is covered with travertine wherever the water 

 was rippled. At one place along this old 

 channel there is a bank of travertine eight or 

 ten feet high. 



These phenomena are to be seen at many 

 other places in the foothills ai'ound the sides of 

 the Santa Clara Valley. 



At Santa Cruz, California, a stream flowing 

 out of a hilly limestone region, where it 

 emerges from the hills, has dej)osited a bed of 

 travertine that is probably fifty feet or more in 

 thickness and covers an area of several acres. 



Perhaps the most remarkable deposits of the 

 kind are those along the western coast of Pales- 

 tine and the southern coast of Asia Minor, 

 where the streams pass over regions of lime- 

 stone. They are frequently spoken of in works 

 upon that region.'^ 



Whether these deposits are all made in the 

 same way or by a single process is doubtful. 

 In the case of the highly carbonated waters of 

 Congress Sj)rings it seems most probable that 

 the deposition of the lime, is due chiefly to the 

 escape of the carbon dioxide when the water is 

 exposed to the air by rippling or spraying. In 

 the cases of streams that run for some distances 

 in open channels before giving up their lime it 

 may be that the deposition is due, at least in 

 part, to the increase of the temperature of the 

 water and the loss of carbon dioxide. But 

 inasmuch as the travertine is formed most 

 abundantly at the falls, it appears that the 

 spraying of the water is an effective agency in 

 the escape of the gas. It is well known also 

 that certain aquatic plants helj) precipitate lime 

 from water by the absorption of carbon dioxide. 

 An interesting case of the kind is mentioned by 

 Clarke, f and other papers have lately been pub- 



* ' Karamania, or a Brief Description of the South 

 Coast of Asia Minor,' etc., by Francis Beaufort, 2d 

 ed., London, 1818. 



t Bull. Neiv York Slate JIus., VII., 195-98. 



