basaltic formation in iceland. 101 



Hredevatn. 



This is a small lake in western Iceland, lat. 64° 41'. A bed of 

 coal occurs in a romantic ravine about 800 feet above the lake, and 

 towards its northern end. The coal is but 18 inches thick, and is 

 immediately under a bed of basalt, with yellow tuffs underneath it. 

 It reappears in a gully 100 yards to the N. W., with a dip of about 

 15° to the S. W. The sectioji is entirely overgrown and covered by 

 earth, and would require much time to uncover ; but I exposed a 

 bed of brown papyraceous shale, and underneath it a short brittle 

 sandy clay, with rootlets and vegetable remains. Above the shale 

 there was yellow tuff; but several hours' search brought forth 

 nothing in the shape of well-preserved leaves, though they are 

 stated to have been found in the tuff at this spot. Another lignite 

 or coal bed is said to occur four hours' ride to the west. 



The coal is used for fuel, but is as costly to obtain, owing to its 

 inaccessible position, as sea-borne Scotch coal. 



Stafholt. 



This locality is a small promontory six or seven miles south of 

 Hredevatn, on the banks of the river, and nearly at the sea-level. 

 The point forms a low cliff, and does not extend beyond 50 yards. 

 The matrix is a coarse yellow brecciated tuff, in which trees of 

 considerable length and girth are imbedded separately, and princi- 

 pally on one horizon, only a few feet above the water. Smaller 

 pieces of wood lie above. These trunks are partly in the condition 

 of lignite, and partly imperfectly silicitied, with their structure 

 beautifully preserved. The deposit is much cut up by dykes. 



Discussion. 



Dr. GwTN Jeffreys said his attention was called to the Icelandic 

 beds with fossil shells by Prof. Steenstrup at Copenhagen in 1869, 

 and further material had been collected by the late Dr. Morch, to 

 whose memory as a conchologist the speaker offered his tribute of 

 admiration. It was remarkable that among the shells there were 

 very few Arctic species. It reminded him of the Moel-Tryfaen 

 assemblage of shells, among which temperate forms occurred in 

 great abundance. 



Prof. JuDD stated that the series of rhyolites brought from the 

 north of Iceland by the author consisted of stony rhyolites, 

 exhibiting banded spherulitic and perlitic structure, passing into 

 pitchstone and obsidian. Some of the rocks are vesicular and even 

 pumiceous, and they are associated with obsidian- and pumice-tuffs. 



Mr. Etheridge bore testimony to the great perseverance shown 

 by the author in working out the Icelandic and Irish beds. He 

 thought the collection of shells from Husavik was of the most 

 interesting character. 



The Author said that many of the shells occur in beds of about a 

 foot thick. The shelly beds are covered by great thicknesses of 

 stratified but unfossiliferous ashes. 



