336 report — 1879. 



the May Hill and Llandovery beds are characterised as such. Hence the term ' Cara- 

 doc ' is inapplicable as a name for the normal portion of the series. The ' Colonies ' of 

 Barrande maybe episodes recurrent on the same area. In the Upper Silurian, the Wen- 

 lock and Aymestry limestone, the Denbigh grits, and Tilestones are episodes. The 

 Carboniferous series present us with the Coomhola grits, Burdie House limestone, 

 Millstone, and Pennant grits, while the Mountain limestone is merely a gradually 

 changing normal deposit. The episodes of the Permian are the fossiliferous lime- 

 stone and underlying marl slate. The absence of the Muschelkalk from England 

 is not regarded as due to its being an episode, but to our deposits as a whole being 

 formed in a distinct area, the true episodes of the period being the Hallstadt, 

 St. Oassian, and Dachstein beds. The Lias is remarkable for its great freedom 

 from episodes, which accounts for the success of its zonal classification, the only 

 exceptions being the Sutton series, and some of the Middle Lias rock beds. The 

 lower Oolites, on the contrary, are almost entirely episodal, none of the beds having 

 a wide range. The Yorkshire deposits were formed in a distinct area, and may 

 cover the period of the Great Oolite as well as the Inferior Oolite, the deposits sup- 

 posed to connect them with the latter being episodes. The rocks above the Corn- 

 brash formed one connected series, as recognised by all German writers and some 

 French, in which the Kelloway rock, the Corallian, and the Portland rocks are well- 

 marked episodes in this country. It is therefore suggested that the term ' Middle 

 Oolites ' should be abolished from the classification of British strata, and the whole 

 be known as Upper Oolites. The various episodes in this series on the Continent and 

 in England will never be truly located until their real character is seen, and it has 

 been by the study of these rocks that the doctrine of episodes has been suggested. 



In the cretaceous series — the Wealden, the Tealby ' series, and parts of the 

 Lower Greensand are episodal, the ironsands being the nearest approach to a normal 

 formation. The Upper Greensands are also episodes ; but the Chalk, though calca- 

 reous, is normal. 



The Lower Tertiaries, like the Lower Oolites, scarcely present any normal 

 deposits, the London Clay being, though argillaceous, episodal in character. 



In the result, the series of sedimentary rocks should be represented not by so 

 many parallel lines, but in many cases by lenticular masses, whose age is denoted 

 by their position — according to a table which presents their true character. It is 

 urged, therefore, that the names proposed — or else some better — be used to dis- 

 tinguish the different kinds of strata and fossils, in order to give definition and. 

 importance to truths which must have long been floating in the minds of geologists. 



7. On the Keuper Beds between Retford and Gainsborough. 

 By F. M. Burton, F.G.S. 



After describing the general position of the beds in relation to the Triassic 

 system, and remarking on the absence of the Upper Mottled Sandstone, as well 

 as the ' Muschelkalk,' in this part of England, the author described the Various 

 strata of the district, as shown on the line between Retford and Gainsborough, and 

 pointed out the want of any division in the beds of the Lower Keuper Sandstone, 

 as iu other localities, ajid the absence of any boundary line between this series and 

 the ' red marls ' above. From the base of the Lower Keuper Sandstone, which 

 rests directly on the ' pebble beds ' at Retford, to the Keuper marls at Gains- 

 borough, beds of light red clays, veins and blocks of gypsmn and thin lines of 

 ripple-marked sandstone occur throughout, and it is only when the highest beds of 

 the Keuper marls are reached that anj' kind of stratification is discernible ; bands 

 of red, blue, and grey earths occurring just before the rocks dip under the Rhsetic 

 beds at Lea. 



The author remarked also on the singular changes in the composition of the 

 gypsum as the higher beds are reached. In the Lower Keupers at Retford, up 

 to the ' red marls' at Gainsborough, this mineral is invariably fibrous or satiny in 

 character ; in the higher beds, however, it changes, at first, to rubbly patches, and, 

 afterwards, to large granular or saccharoid blocks. 



