Relations of the RhcBtic Beds in Somersetshire. 197 



and merely confirms the opinion that there is no abrupt line between 

 the two series of deposits. 



The junction of the Lower Lias with the Eh^tic beds is in many 

 parts of Somersetshire well marked, and this is more particularly 

 the case on the north than on the south of the Mendip Hills. Taking, 

 as Mr. Moore does, the White Lias with its top "Sun-bed" or "Jew- 

 stone,^ as the upper limit of the Ehsetic beds, the change from its 

 even-bedded and clean-looking white limestones to the irregular blue 

 and brown earthy and argillaceous limestones and clays of the 

 Lower Lias, may usually be detected at a glance in most quarries, 

 or even, as Mr. Moore remarks, from the window of a railway- 

 carriage, when passing through a cutting where these rocks are 

 exposed. 



This is the case generally all over the area occupied by these 

 rocks between the Avon and the Mendip Hills.^ 



To the south of this range in many places the junction is not so 

 apparent, the lithological change is more gradual, so that it is often 

 difScult to say where the junction is, even when the beds are traced 

 out carefully on the ground. 



Thus, in the railway-cutting west of Shepton Mallet Station, the 

 junction with the Lias is clear and well marked ; but further west, 

 only five miles distant, at Milton Lane, near Wells, also near Wed- 

 more, and along the Polden Hills, the junction is not so distinct. 

 The limestones at the base of the Lower Lias become paler in colour, 

 and approach in character some beds of the White Lias, while the 

 clays are replaced by soft white marls, and higher up by what have 

 been aptly termed slaty marls. There are occasionally several beds 

 in the Lower Lias which closely resemble the " Jew-stone." Fur- 

 ther, the most abundant fossils at the junction, Ostrea Liassica and 

 Modiola minima, are common to the Lias and Eh^etic beds. 



Towards the Blackdown Hills the White Lias has a meagre 

 development, whilst at Watchet it is still more attenuated. 



The stratification of the Lias and Eheetic beds is always con- 

 formable, and although the change of sediment is more marked in 

 some places than in others, we have no reason on stratigraphical or 

 lithological grounds to separate the two, any more than we should 

 separate the black paper-shales from the White Lias. Indeed, the 

 change is no greater than that which is repeated in the Lias in the 

 alternations of clay and limestone which compose its mass. 



We will now turn our attention to the junction of the Ehaetic 

 with the Keuper Marls. Here, likewise, there is a perfect conform- 

 ability and a clear passage from one into the other ; everywhere the 

 evidence is unequivocal. Commencing with the Eeuper beds, we find, 

 as has frequently been pointed out, that in ascending the series, the 



> " Sun-bed" is the term applied by quarry-men in the neighbourhoods of Bath and 

 Radstock to the top bed of the White Lias. It is a hard cream-coloured or bluish 

 limestone with a conchoidal fracture. The term "Jew-stone" is applied to the same 

 bed near Wedraore and along the Polden Hills. 



^ We must refrain from details, as these will appear in a Geological Survey Memoir 

 on the district, now in course of preparation. 



