356 Proceedings of the Royal Physical Society. 



some relation to fact ; but without going into the history of 

 this opinion, it will be enough to notice, that as far as I am 

 aware there is but one place in Lewis where the remains of 

 forest trees are to be found. The roots of firs over twelve 

 inches in diameter occur near Balaline, in the parish of Lochs, 

 and only there. These roots are always on the clay soil, for 

 neither bush nor tree is found with its roots in the peat. 



But although in a thousand cases the section of a peat bank, 

 from its surface to its base, exhibits only a succession of marsh 

 plants, a patient observer will here and there find a spot 

 where the foundation of the peat is a floor of twigs and leaves. 

 This, as stated before, bears only a minute proportion to the 

 moor peat of the country. When examined it appears to be 

 made up in great part of the twigs of the birch, but I have no 

 doubt that the berry and bush of the mountain ash, the larch, 

 the aspen, and the willow could be detected. In fact, it so 

 happens that in this strange country, where many of the 

 manners of the tenth century still exist, the method by which 

 this peat of scrub and brushwood was formed can still be 

 seen. On the small islets in the lakes, to which neither 

 sheep nor cattle can gain access, a dense mass of scrub still 

 survives. The heather will grow four feet in height, and 

 above that may be seen the red berries of the mountain ash, or, 

 if in spring, the catkins of the willow, or the pendant leaves 

 of the aspen, with briers and brambles to interlace the whole. 

 In the face of some cliffs and banks, and even in a few re- 

 mote spots, the holly, hazel, aspen, birch, and willow, still 

 struggle against an adverse climate as they did a thousand 

 years ago. 



I have been thus particular in pointing out the limited 

 quantity of wood peat, and where it occurs, its position, rest- 

 ing upon the boulder clay, for a purpose to be more particu- 

 larly described at the close of this paper ; and I pass on to 

 notice some important geological changes that have taken 

 place in the most recent or peat-forming era. 



My official duties led me last summer over several hundred 

 miles of the most tortuous coast-line imaginable. Between 

 North and South Uist lies the large island of Benbecula, and 

 about five hundred others of different sizes and shapes ; most 



