379 



Throughout the Sjnnatus Zone, about 40 ft. in thickness 

 presents the same lithological features, and the same leading 

 species. Unhappily, when we look for what will serve us to the 

 Eastern coast of Scotland, we see magnificent sections of 

 Middle Lias in Sutherland, but the very part we want is gone 

 or concealed. Some 80 ft. of the lower clays of the Middle 

 Lias (subdivision Gamma of Quenstedt) exist, and the proba- 

 bility is that the intervention of a great transverse fault, has 

 brought down the clays of the Middle Oolite against the clays 

 of the Middle Lias, and the portion we would fain summon as 

 a witness, is unavailable, at least so far as the Spinatus Zone is 

 concerned, yet they testify to what is of vaster importance than 

 the existence of any particular Zone, namely, to the existence 

 of the Jurassic sea in this latitude. Mr. Jijdd in his able 

 disquisition on the " Secondary Eocks of Scotland " (first part)* 

 leaves the existence of the top of the Middle Lias an open 

 question ; for the occurrence of numerous boulders with Jurassic 

 fossils of Middle Lias from the upper beds, so abundant in the 

 Elginshire drifts, raises the hope that the parent beds may in 

 places underlie the vast masses of Boulder clay which cover up 

 the country. It is to be wished that the learned author will be 

 enabled to revert to this interesting topic in the 3rd. part of his 

 valuable work, his 2nd. part is on the "Volcanoes of the 

 Highlands." In England we begin with the North coast of 

 Yorkshire, which affords us sections most relevant to our point ; 

 here, fortunately, we possess the clearest and fullest light. The 

 works of Prof. Phillips, edited by Mr. E. Etheeidge, F.E.S., 

 "The Yorkshire Coast" 1875, and Messrs. Tate and Blake, "The 

 Yorkshire Lias," (Van Voorst, London, 1876,) give us all that we 

 require. According to Prof. Phillips, the exposure of the 

 Spinatus Zone is well shown in Plate XX, where in the harbour 

 at Staithes, the Spinatus sands are to be seen capping the 

 Colborn Nah, with a thickness of 25 feet, and are on the other 

 side of the harbour, thrown down to the base of the Cliff. In 

 other parts of the coast they are much thicker. The Professor 

 singles out the Staithes Chffs, as they offer a most advantageous 



* Quarterly Joiuiial, Geol. Soc. XXIX, 'J7, London. 



