J. D. Dana — History of the Changes in Kilauea. 355 



The lavas exuded through the crust from the liquid mass 

 below, above alluded to as making seams, streamlets and 

 knobby surfaces, are covered sometimes with separable scoria- 

 ceous glassy crust, though commonly having a solid glassy 

 exterior half an inch or so thick. 



9. The wrinkled surfaces or tapestry-like folds of the flowing 

 lavas. — While looking at the small lava lake, the making of 

 the tapestry-like folds, so common a fluidal feature of the lava- 

 streams of Hawaii, was well exemplified. A stream of lava 

 came out from beneath the cone and flowed obliquely across 

 the lake, making the folds or wrinkles by its onward move- 

 ment in the thin crust which surface cooling had produced ; 

 and the wrinkles were convex down-stream because of the 

 greater velocity at centre. The accompanying figure repre- 



sents, reduced, a small portion of the stream. At one time a 

 lateral shove took place along one of the fissures in the crust of 

 the lake, and the next moment the margin was rolled over into 

 a long fold or wrinkle, and then by the more rapid movement 

 of the middle portion, a large part of the fold became twisted 

 into a rope. Thus fold may follow fold, and make a group or 

 series of rope-like folds ; and tapestry wriukles become rope- 

 like by a similar method. 



The tapestry-like folds of the surface of streams are some- 

 times folds simply in the scoria-crust; but they commonly con- 

 sist of the more solid lava also, or of that alone where the 

 scoria-crust is absent. This rope-making goes on over parts of 

 outflowing lava streams. Sometimes, in connection with the 

 making of the long ropes, the crust, where thin, becomes bent 

 upward so as to have a long empty space a foot or two deep 

 beneath the brittle cover. It is a trap for the incautious trav- 

 eler, but it usually startles without injuring, yet serves to 

 point a paragraph about the dangers of the crater. 



On Plate IV, which represents the general aspect of the floor 

 of Kilauea (and of many lava flows elsewhere) there are exam- 

 ples of the tapestry-like folds, and some of the small folds are 

 twisted rope-like. 



10. Dome-shaped bulgmgs of lava-streams made sometimes, if 

 not generally, after the stream has flowed on. — Such bulgings, the 



