MOORE ABNORMAL SECONDARY DEPOSITS. 459 



or brackish-water deposits of the Upper Trias, I might have hoped 

 to find somewhere on so extended a coast-line as that under 

 consideration. 



2. The Ehcetic Beds. — Since the publication of my paper on the 

 " Zones of the Lower Lias and the Avicida-contorta Zone," in the 

 Journal of the Geological Society in 1861, much attention both in 

 this country and on the continent has been given to the Ehaetic 

 formation, and many valuable memoirs have appeared almost simul- 

 taneously. At this time it is not my intention to give descriptions 

 of the numerous Ehaetic fossils I have added to the lists since the 

 above publication, which I hope soon to do. I rather desire to 

 describe some admirable typical sections which several new railway- 

 cuttings have opened up, and to notice also the mode of their occur- 

 rence in the Eadstock and other districts, and in South "Wales. The 

 sections previously known, and where they can still be studied, are at 

 East Cliff and Westbury on the Severn, "Watchet, Pyle Hill, Uphill, 

 Saltford, Beer Crowcombe, Shepton Mallet, and Long Sutton in 

 Somersetshire, and at Penarth Cliffs in South Wales. Additional 

 sections are now open at Patchway, on the South Wales Union Eail- 

 way, at Hatch Beauchamp, on the Chard and Taunton Eailway, 

 and at Willsbridge and Newbridge Hill, on the Bath and Mangots- 

 field line. 



Since, in these sections, the beds of the Lower Lias are in every 

 instance found reposing upon the Ehaetic series, it will be more con- 

 venient, especially as I shall have to point out frequent evidences 

 of their unconformability, and of the absence of some members of the 

 Lower Lias, to consider the two formations together ; and this will 

 also the better enable me to correlate the South Wales sections with 

 them. 



One of the most desirable points in connexion with geological in- 

 vestigation is to give attention to the passage-beds between the esta- 

 blished series of formations — to endeavour to find how they lead one 

 into the other, and how the succession of organic life may have been 

 modified thereby. In order to arrive at any satisfactory conclusions 

 on these subjects, it will be manifest that such formations must be 

 studied, not where they are in abnormal conditions (as is gene- 

 rally the case where they come in contact with older unconform- 

 able deposits), but where there certainly is an unbroken and unin- 

 terrupted passage from the one into the other ; and fortunately there 

 are such sections. These I shall now give, and with them, as 

 typical, afterwards compare their equivalents elsewhere. 



The horizon of the Ehaetic beds commences above the Upper 

 Keuper marls with grey or bluish sandstones or marlstones. Although 

 varying in thickness, they are present in every section with which I 

 am acquainted ; and as they contain Ehaetic fish and other remains 

 at Watchet, Shepton, Willsbridge, &c., they form a distinct base- 

 line for the formation ; and above are included all the beds to the 

 uppermost *' White Lias" (''Sun Bed" of William Smith). They 

 may therefore be divided into two groups — the Avicula-contorta and 

 Bone-bed shales, and the " White Lias." Although there are local 



