248 THE JOURNAL OF BOJTANl 



country to be a competitor for favour. The valley of the Severn 

 at Gloucester, according to WiUiam of Malmesbury (1100 to 

 1150 ?), was the chief vine-producing district in England, there 

 being more vines and better grapes grown in that county than 

 in any other part of England." 



This evidence for a distinct change of climate for the worse of 

 late years is not an isolated case. Sir Joseph Banks, writing 

 about five dug-out boats of oak found in Lincolnshire just before 

 1816, says : " All these canoes are remarkable for the free grain of 

 the oak timber, so that millwrights and carpenters who examined 

 it declared that in their opinion it was of foreign growth, and the 

 produce of a warmer country."! Practically, the wood of all 

 species in the later middle period peats has this same open 

 texture, while that of the post-glacial and older middle period 

 peat-beds is close-grained and that of the very latest peats is closer 

 grained, approximating to the wood of to-day. There seems to 

 be a perfectly demonstrable transition from the woods of semi- 

 arctic conditions to trees grown in a climate much milder than 

 ours, with warmer winters and longer summers. The whole 

 subject wants systematically enquiring into, wherever peat-wood 

 is discovered, if its exact horizon can be ascertained. 



Peat has been forming in Lincolnshire, with large gaps no 

 doubt, from the retiring of the chalky boulder clay ice-sheet to the 

 present day. This has taken place under slightly varying condi- 

 tions of geological elevation and depression and a more regular 

 and distinct change of climate. Eor our purpose the geological 

 evidence may be disregarded, as it is too trifling to affect the 

 climate. The whole county being more or less formed of lime- 

 stone, the peats generally are of the Hypnum in contradistinction 

 to the Sphagnum moss type, i. e., they were formed in limestone 

 rather than in neutral or acid waters. This is, however, only their 

 general character ; there is no iron rule. At Scotton Common 

 to-day Eriojphorwn vaginatum, an acid peat species, is found not 

 far from Helleborine longifolia, a lime-water peat species. These 

 beds overlie one another in section on the common. In one 

 place I found Hypnum beds with Betula tomentosa, overlaid by a 

 Sphagnum bog with a clearly defined Eriophorum vaginatum bed 

 between. In another spot, I have been told, this order is reversed ; 

 but of this I have no personal proof. 



It soon becomes clear to anyone studying our peats that three 

 periods can be detected in them : — (3) An Historical, (2) a Middle, 

 and (1) a Subarctic Period. These may be classed roughly in 

 Lincolnshire as follows, by their tree flora : — 



The Historical Period is that of Ulmus montana, Fraxinus, 

 and Ilex. Looking from the present backwards, of fairly close to 

 open-grained woods. 



The Middle Period at its latter end is one of open-grained 



• William of Malmesbury' s Hisiorica Novella ; Mr. G. Abbey, Journal 

 of Horticulture, 1899. 



t Journal of Science and Arts, vol. i. p. 244 (1816). 



