308 MR MILNE ON THE MID-LOTHIAN AND EAST-LOTHIAN COAL-FIELDS. 



discovery of an elephant's tusk in cutting (for the Union Canal) through what the 

 author terms the " old alluvial cover." These are the only publications I have 

 heard of, which throw light on the various deposits that cover the rocks of the 

 south of Scotland. Indeed, the subject is not one naturally susceptible of accu- 

 rate or extensive investigation ; — and even when investigated, it is not very sus- 

 ceptible of a description that is precise, or that can be readily apprehended. In 

 endeavouring to examine these deposits, the geologist finds few places where they 

 are visible ; and unless they are seen at the very moment they happen to be opened 

 up, they soon, in consequence of their loose and friable nature, become concealed 

 under a mass of rubbish. In this respect, therefore, the subject presents greater 

 difficulties than the study of the stratified rocks, — the croppings of which are to be 

 seen, and may be easily examined, in old quarries, in the channels of rivers and 

 burns, and even along the sides of roads and ditches. 



The other difficulty which the geologist has here to contend with, is the want 

 of appropriate terms to convey ideas of what he has seen ; — and what is no less 

 perplexing, there is the existence of several terms used in common language to 

 signify some of these deposits, which terms, however, are of uncertain and varia- 

 ble import. So long as both of these difficulties remain, any distinct description 

 or information on this subject, must be next to impossible ; — and the opinions of 

 geologists themselves must continue fluctuating, and be at perpetual variance. All 

 phrases, such as " old alluvial cover," — " till" — " recent alluvial cover" — " diluvial 

 debris" are dangerous, when used in description, unless at the same time the 

 thing described be otherwise very specially characterized. General phrases are 

 no doubt useful and necessary, in order to avoid repetition ; but the great desi- 

 deratum is a distinct and copious description of the characters and contents of 

 the deposits themselves. 



In describing the different accumulations now referred to, it will lead to pre- 

 cision to follow a certain arrangement or classification. A very convenient one 

 is suggested by the order in which they occm-, in respect of position ; certain of 

 these deposits, with well marked characters, being found throughout the district. 

 always in the same relative positions. I think it possible to identify and indi- 

 vidualize at least seven formations, each of which has separate characters in re- 

 spect of texture, contents, and appearance, — and each of which belongs probably 

 to different epochs. I wiU now enumerate them, beginning from the sm-face ; 

 and in doing so, I will, for the sake of convenience, designate them by particular 

 terms. 



(1.) The existing soil, supporting vegetation. 



(2.) Upper covering of gravel and boulders. 



(3.) Deposit of sand and shells. 



(4.) Beds of fine sand. 



(5.) Beds of fine clay. 



