HARDWICKE'S SCIENCE-G OSSJP. 



271 



they occur has been split and cracked in all directions, 

 30 that it sometimes happens that these cracks unite 

 with each other thus forming a core ; this, from long 

 weathering becomes gradually loose, and the action 

 ■of the waves soon works out this core in the form of 

 honldas, the remains of which on the floors and in 

 front of these caves testify to the manner in which 

 they were formed. 



The coast-line from here to Grosnez is very grand, 

 and at L'Etac the syenite is overlaid by clayslate, 

 which on the shore exists in extensive ledges forming a 

 rocky expanse at low water; here galena has been 

 obtained, but in very small quantities ; the syenite in 

 many places is intrusive, and it is possible to obtain the 

 two rocks even in a small hand specimen showing 

 ■the junction. 



After leaving L'Etac we came to the long flat 

 sandy bay or St. Ouen, with its weird, dreary fresh- 

 water pond ; the recent geology here is well worth 

 careful study, the blown sand is gradually encroaching 

 inland, destroying what once was good pasture. This 

 part of the island contains evidences of more than one 

 change of level, for not only are older sand-hills 

 showing traces of a vegetation, being worn down to 

 supply a new series of sand-hills, but slabs of peat 

 are frequently washed ashore from a lower and sea- 

 covered area. Some distance inland, but still in the 

 i:iarish of St. Ouen, we can trace on the high ground 

 ■ a well-defined raised beach, the triturated pebbles in 

 which are as characteristic of wave action as the 

 ibeaches of to-day several hundred feet below. 



The lower part of this large bay is bounded by cliffs 

 ■of syenite, which, stretching round by St. Brelade's 

 .and Portelet Bay, present one of the best rocks in the 

 island for practical purposes ; that of St. Brelade's 

 district being particularly good. At Portelet Bay 

 there is a beautiful form of syenite, the felspar being 

 very massive, and reddened by sea action, containing 

 large fragments of white quartz. Working round 

 to St. Aubin's, we again come upon the clayslate, a 

 fine quarry of which, containing calcite and traces of 

 copper, is worked at St. Peter's. Here may be seen 

 a very fine example of ripple marks. Perhaps no part 

 of the island possesses such fine examples of branch- 

 ing valleys, again supporting the theory of a local 

 glaciation, as does this charming district, those of 

 St. Peter and St. Lawrence being the most charac- 

 teristic and beautiful. 



The particularly noticeable ridge which seems to 

 form the « estern boundary of the town and which is, 

 or was, kni/wn as Gallows Hill, is composed of a clay- 

 stone porphyry of a most peculiar form. In one part 

 the matrix is a fine greenish-black containing pale 

 coloured, lenticular crystals, the weathered form be- 

 coming a dull yellowish-brown ; in other parts the 

 crystals are accompanied by amygdaloidal cavities, 

 and others again contain small quartz crystals 

 scattered through the matrix. As may be imagined, 

 it is easy to obtain specimens of this remarkable 



rock which exhibit the most beautiful and interesting 

 structures. Traces of carbonate of copper in some 

 places occupy whole surfaces of cleavage fracture, 

 but there is scarcely sufficient evidence of it to 

 suggest its existence in any quantity. This ridge is 

 intersected by a vein of basalt which, although 

 much decomposed, shows some fine examples of 

 concentric structure. 



The decomposed syenite which occurs in so many 

 parts of the island, is largely worked and exported 

 for gravel ; if well worked it forms excellent paths, 

 and is used for that purpose nearly all over the 

 island. 



We have thus taken a rapid and very superficial 

 glance at the various points of geological interest as 

 they occur, in a journey round the coast-line of the 

 island ; and we think that there are veiy few locali- 

 ties that would not well repay a careful investigation, 

 and which would, moreover, be of great interest and 

 instruction to the investigator. 



{To 6c continued.') 



RECREATIONS IN FOSSIL BOTANY. 



Dadoxylon. 



No. VII. 



By James Spencer. 



THERE is a very singular fossil, met with in the 

 sandstone rocks of carboniferous age, especially 

 in those of the millstone grit and the coal-measures, 

 which is well known to fossil collectors under the 

 name of Sternbergia. Occasionally it is found in its 

 natural or round state, but more commonly it has 

 been flattened by pressure into an oval form. It is 

 characterised by being marked by a series of trans- 

 verse bars, somewhat like the rungs of a ladder, or, 

 more correctly, like the transverse bars seen on the 

 woody vessels of scalariform tissues, only they are 

 more irregular in form and consist of a series of 

 grooves and ridges. This curious fossil was named 

 Sternbergia, in honour of Count Sternberge, a cele- 

 brated geologist of former days, and at that time and 

 for a long time after, it was thought to have been a 

 distinct plant. In the same quarries, there occurs 

 along with Sternbergia, but much more rarely, 

 another fossil plant of larger and more tree-like 

 aspect. It generally assumes a rounded trunk-like 

 form, and the specimens vary considerably in thickness, 

 from a few inches to two or three feet, and from a 

 few inches to many feet in length. It is recorded by 

 Lyell and other writers that in some places these tree- 

 like forms have been found of great length — from 

 60 to 70 feet or more. They have no external 

 markings, by which their fragments can be readily 

 distinguished from other fossil plants like Calamites, 

 Lepidodendron, Sigillaria, &c., and in fact, it is 

 chiefly through the absence of these Calamitean 

 and Lepidodendroid markings, combined with their 



