VAUX — VOLCANIC ROCKS OF ICELAND. 
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1. Gjas. 2. Lava delage. 3. Original surface. 4. Thing^'alla snnk to a lower level. 
" 1, 1 " are the two chasms, called respectively Almanna Gja, or Main 
Gja, and Hrafna Gja, or Raven's Gja. In the act of disruption the 
sinking mass fell in, as it were, upon itself, so that one side of the Gja 
slopes a good deal back as it ascends ; the other side is perfectly per- 
pendicular, and, at the spot I saw it, upwards of a hundred feet high. 
In the lapse of years, the bottom of the Almanna Gja has become gra- 
dually filled up to an even surface, covered with the most beautiful 
turf, except where a river, leaping from the higher plateau over the 
precipice, has chosen it for a bed. You must not suppose, however, 
that the disruption and land-slip of Thingvalla took place quite in the 
spick and span manner the section might lead you to imagine ; in some 
places the rock has split asunder very unevenly, and the Hrafna Gja 
is altogether a very untidy rent, the sides having fallen in in many 
places, and almost fiUed up the ravine with ruins. On the other hand, 
in the Almanna Gja, you can easily distinguish on the face marks and 
formations exactly corresponding, though at a different level, with 
those on the face opposite, so cleanly were they separated. 
" 2 " is the sea of lava now lying on the top of the original surface. 
Its depths I had no means of ascertaining. 
" 3 " is the level of the surface first formed when the lava was still 
hot. 
" 4 " is the plain Thingvalla, eight miles broad ; its surface shattered 
into a network of innumerable crevices and fissures, fifty or sixty feet 
deep, and each wide enough to have swallowed the whole company of 
Corah. At the foot of the plain lies a vast lake, into- which indeed it 
may be said to slope, with a gradual inclination from the north, the 
imprisoned waters having burst up through the lava strata as it sub- 
sided beneath them. Gazing down through their emerald depths, you 
