since the Great Ice Age. The rivers, however, have carried down large 
quantities of gravel and sand with which they have silted up the heads 
of the firths, thus forming low plains which in their turn constitute 
‘he main portions of the irrigated and marshy meadows in Iceland. 
In different parts of the country there may be found rhyolite forma- 
tions, but their sporadic occurrence makes them of minor importance. 
Other kinds of rock than basalt and its varieties rarely occur, except 
the gabbro and granophyre formations, found in the neighbourhood 
of HornafjérBur in south-eastern Iceland. The crag formations in 
Tjbrnes are, from a geological point of view, of great interest. The 
‘hickness of these strata attains in places some 700 metres. } 
The soil all over the country is preity uniform as regards its chemical 
constitution, but it varies in appearance according as the place is high 
above or near the sea level. Close to the jtkulls there is practically 
no soil, at least no organic matter worth speaking of; there is either 
the naked rock, terminal moraines, or sands, but no vegetation of any 
kind. As we come lower down, however, the vegetation gradually 
increases and the stratum of humus grows in thickness, so that in 
many places in the lowlands it is more than a metre deep. As the 
climate is rather chilly decomposition has played a rather insignificant 
part in shaping the surface features of the land, as compared with 
such adventitious matters as glacier detritus, volcanic ashes, and earth 
carried by the winds. These have settled in sheltered places, in hollows, 
in woody districts, and even on grassy plains, the depth of the soil 
therefore being greater here than elsewhere. On the other hand, where 
the wood has been laid waste or the sward broken up, the soil, when 
in a dry state, is apt to be blown away, as the matter composing it-is 
loose and of light weight. 
Where the soil is moist, bog plants grow, and in course of time 
peat is formed, which in some places has attained a thickness of from 
two to three or (rarely) even 10 metres. It is seldom found in a pure 
state, but with layers here and there of sand, of old volcanic ashes 
and clay carried to the bogs by the spring freshets, Yet peat is consider- 
ablv used as fuel bv the neople. 
CLIMATE 
Iceland has an Oceanic Climate — that is, one of moderate heat 
and cold. Though the island is large, the differences in temperature 
between the coast and the interior are not very marked, and con: 
sidering its high latitude, Iceland has, on the whole, a much higher