30 F. S. Beudant on the Calcareous Tufas cf Hungary. 
fas, which are daily formed by chemical precipitation from mat- 
ters which the waters dissolve, while traversing the mineral mass- 
es ; and, on the other, the heaps of different matters, continually 
detached from the mountains, which the waters of rains, torrents 
and rivers, daily extract from all parts, and carry to the bottom 
of the neighbouring valleys, or transport, in their course, to the 
midst of distant plains. It is these latter deposits, whose 
mass is always increasing, which, after being once formed, are 
again themselves affected by the waters, transported from one 
place to another, undergoing various changes, that I would more 
particularly designate by the name of Alluvion. They form, in 
some measure, the continuation of the arenaceous deposits which 
have been already described, and which may be regarded as co- 
lossal alluvia of an old world. It is even sometimes difficult to 
distinguish them, because they are the same materials, which, 
after having been worn off in one point, have been transported 
without any change to another. But the difference which exists 
here is more easily perceived than expressed ; and besides, in 
these deposits, there occur enveloped together, debris of all sorts, 
derived from various kinds of rocks over which the waters have 
rolled, plants which grow at the surface of the soil, terrestrial or 
aquatic shells of all kinds ; debris, in short, of all that exists at 
present upon the earth, whether natural productions, or even 
the products of human ingenuity. There result, in consequence, 
deposits which are distinguished from all others by a multitude 
of peculiar circumstances. 
Among the calcareous tufas which occur in Hungary, two 
species should, perhaps, be distinguished ; one which proceeds 
from old deposits, of the formation of which no remembrance is 
preserved, and which, having long since ceased to increase, ap- 
pear to have belonged to an ancient order of things ; another, 
again, which comprehends deposits evidently originating from 
sources which are still to be discovered in the same places, and 
which do not cease to acquire daily augmentations in the same 
manner as they have commenced. To the first type must be 
referred the calcareous tufas which occur above the last houses 
of the suburb of Buda, and which extend from thence to the 
gravelly bills of Saint Andre. It is a pretty considerable mass, 
which terminates in a very even platform, the sides of which are 
