Phytogeographical Excursion in the British Isles. 28 t 
of the moss still continues, but is largely aided by peat cutting; 
the parts most affected bear a mixture of Eriophorum and Callunci 
and are eventually colonised by birch and Scots pine from 
neighbouring woods and plantations. Thus by the time the Erio- 
phorum has disappeared regular birchwood is formed, with pine, 
mountain ash, yew, sallows, etc., and in places a ground vegetation 
of Molinia Vaccinium, etc. The wetter parts of the moor are 
still occupied by Sphagnum-bog. Sections of the peat show a very 
similar sequence to that of the “Burton Lake” peat, except that 
the upper Sphagnum- peat passes up into a thin layer of Eriophorum- 
peat on which grows the existing Eriophoretum, while below, the 
fen peat is separated from the Sphagnum-peat by birch and pine in 
situ and is based on an estuarine silt containing the roots of trees. 
Here then we have two complete successions, that of the fen and 
that of the moor, each culminating in a wood-association, while the 
remains of a very ancient wood destroyed by the growth of the fen is 
found at the extreme base. The remains of an ancient “ corduroy 
road ” consisting of logs placed transversely occur in the midst of the 
Sphagnum- peat. Mr. Rankin’s excellent work on these lowland 
moors was the subject of general congratulation. A brief account 
appears in Types of British Vegetation, but it is to be hoped that a 
fuller account will shortly be published. The party afterwards visited 
the gardens of Levens Hall with its famons topiary work, and in 
the evening travelled from Oxenholme to Penrith, where they were 
met by Dr. F. J. Lewis. 
On Sunday, August 13th, an early start was made for Crossfell, 
the party driving to Kirkland at the foot of the mountain. The 
Crossfell ridge consists of alternating bands of gently inclined 
limestones, flags and grits. The western escarpment is formed of a 
series of terraces, the steps being formed of limestone, free from 
peat, and covered by a thin soil forming typical limestone grassland 
with Festuca ovina, Sesleria ccerulea, Agrostis vulgaris, Kceleria 
cristata, Poa pratensis, and various “ calcicole ” plants. The sand¬ 
stones and flags form slightly inclined platforms between the steps, 
and are covered with siliceous grassland, largely dominated by 
Nardus stricta and jfuncus squarrosus, with stunted moor plants 
such as Calluna, V accinium Myrtillus, etc., in places where there is 
a distinct accumulation of peat. On the western side of Cross Fell 
itself there is no extensive moorland association, but on adjoining 
parts of the ridge, moor comes down to an altitude of about 600 
metres. Dr. Lewis is, however, of opinion that the whole western 
face of the range was at one time covered with peat, that the local 
patches of peat on the western side of Cross Fell are the remains 
of this extensive mantle, and that the cause of its disappearance is 
probably to be found in the increasing dryness of the climate. He 
sees evidence for this view in the widespread degeneration of the 
moor formation throughout the British Isles, as shown by the 
occurrence of “ retrogressive moor ” (a term due to Dr. Moss, who 
does not, however, assign its origin to a change of climate) on many 
high plateaux. This retrogressive moor is characterised by the 
erosion of the peat and by the constant occurrence of Vaccinium 
Myrtillus, Empetrum nigrum and Rubus Chamccmorus on the hags 
between the erosion channels. The association occurs on the hills 
