204 C. Lapworth — Geology of Galashiels. 



beds with the overlying Lias, but about half a mile higher up the 

 Fig. 2. stream to the east, the bank, 14 feet 



high (Fig. 2), presents the following 

 section — a, drift, two or three feet 

 thick ; B, limestone bands, three or four 

 inches thick, with obscure casts of 

 fossils ; o, dun-coloured sandy shales, 

 eight feet thick ; d, bluish-black fissile 

 shales of unknown thickness, occurring 

 in the bed of the brook, and closely 

 resembling b or d in section, Fig. 1, 

 of which it may possibly be the upper 

 portion. 

 Section half a mile SE. of Audiem. ^^ Etheridge has determined from 



these beds Myacites auconoides, Modiola minima, and Pullastra areni- 

 cola, and suggests that the bed c, containing Myacites, is probably 

 Lower Lias. I failed to find Avicula contorta in any part of this 

 section. 



IV. — On the Lower Silukian Kocks of Galashiels. 



By Charles Lapworth, Esq. 



Part I. 



(PLATE VIII.) 



THE Lower Silurian rocks of Scotland, largely doTeloped as they 

 are in the south, and in spite of the great labour that has been 

 bestowed upon them, are by far the least known of all the fossiliferous 

 formations of that country. While the maps of the Government Geo- 

 logical Survey are coloured in all the subdivisions of the strata of 

 the other formations included in their area, the Lower Silurians are 

 merely indicated by a common purple tint, and not the slightest 

 attempt at a subdivision is made. Even the siagle bed of Limestone 

 they contain, below the horizon of that of the W. coast, is doubtfully 

 referred to the Llandeilo, and the sign of interrogation is carefully 

 placed before its title. Nicol, Harkness, J. C. Moore, and many 

 other eminent geologists, have worked different portions of these 

 ancient deposits since the publication of " The Silurian System," but 

 as yet very little progress has really been made in correlating its 

 different parts with those of the type formation of the sister country. 

 Now, this want of accurate information is due to two causes. 1st 

 — The strata are so rapidly folded and contorted, and are conse- 

 quently so intricate and confused, while, at the same time, they 

 present so few differences lithologically, that anything like a physical 

 separation of its masses is well nigh impossible ; and 2nd — The 

 whole formation, with the exception of a few isolated bands of Lime- 

 stone towards the west, and some bands of Anthracitic shale that 

 make their appearance about the geographical centre of the system, 

 seems to be nearly destitute of organic remains. 



