46 
Dr MacCulloch on Peat. 
shells, of which an account was given by the writer of this arti- 
cle in a paper on Glen Tilt, published in the Geological Society’s 
Transactions. 
It is easy to see how lake-peat may alternate with strata of 
clay, and of gravel and sand. These have been the result, as 
at the estuaries of rivers before noticed, of occasional floods, 
carrying with them so large a quantity of earth as to suffocate 
and destroy for a time the process of vegetation ; and it is easy 
to conceive how the occasional addition of such transported ma- 
terials, might, for a certain time, impede the re-establishment of 
a vegetating surface, so as to form an earthy stratum of consi- 
derable depth. It is also easy to understand how the gradual 
addition of earth, in a quantity insufficient to destroy vegeta- 
tion, may, instead of peat, lead to the production of an ordinary 
vegetable soil, and how the margin of a lake, in the act of fill- 
ing, will, instead of a peat-bog, become a fertile meadow. 
In concluding this sketch of the formation of lake-peat, it is 
interesting to observe the simplicity and certainty of the pro- 
cesses by which water is converted into land in the interior of a 
country, as it is near the marine estuaries of rivers. 
The plants which chiefly contribute to the formation of this 
kind of peat, are the following, and they are separated, in some 
measure, according to the regions which they occupy in the wa- 
ter or on its margin. 
Conferva bullosa. 
Lemna minor. 
trisulca. 
Nymphaea alba. 
lutea. 
Potamogeton natans, 
heterophyllum ; 
and others of this genus. 
Chara vulgaris. 
Hippuris vulgaris. 
Callitriche verna. 
autumnalis. 
Myriophyllum spicatum. 
verticillatum. 
Ceratophyllum demersum. 
Utricularia vulgaris. 
minor. 
Sparganium natans. 
erectum. 
Ranunculus aquatilis. 
Plydrocliaris morsus raiias. 
Arundo phragmites. 
Scirpus lacustris. 
Lobelia dortmanna. 
Scirpus acicularis. 
setaceus ; and others. 
Subularia aquatica. 
Isoetes lacustris. 
Alisma plantago. 
ranunculoides ; and 
others. 
Sagittaria sagittifolia. 
Butomus umbellatus. 
A corns calamus. 
Phalaris arundinacea. 
Poa aquatica. 
Juncus conglomeratus. 
effusus ; and others. 
Schcenus mariscns; and others. 
Menyanthes trifoliata. 
Comarum palustre. 
Some Equiseta. 
