14 J. C. Ward — Development of Land. 



After the elevation of the land just spoken of, the eruptions, being 

 sub-aerial, gave rise to many volcanic hills, which now agreeably 

 relieve the monotony of the plains. 



At what precise period Vesuvius began to exist,^ whether at first 

 as a sub-marine volcano, or not until the post-Pliocene elevation 

 took place ; whether its first eruptions were coeval with those of the 

 Phlegrsean Fields ; or whether the Neapolitan group, as a whole, 

 came into activity simultaneously with that around Eome ; are points 

 not easily determined. It is sufficiently evident, however, that the 

 birthtime of most, if not of all, was just about the close of the 

 Pliocene period ; that is to say, their products of eruption directly 

 overlie strata of Pliocene age. 



Such, in brief, is a sketch of Italian geological history ; some of 

 the most noteworthy points of which seem to be the following : — 



1. The geological records date back only to Jurassic times, and 

 there is no direct evidence of land over this area until late Secondary 

 or early Tertiary. 



2. The formation of Italy has been eff'ected in a very simple 

 manner, namely, by the upheaval of three consecutive marine for- 

 mations into a long chain of mountains, and by the deposition round 

 this long island of marine strata belonging to the Miocene and 

 Pliocene periods, and their subsequent moderate upheaval. 



3. The time through which this history carries us back divides 

 itself into three separate periods as regards action from below. 1. 

 A period of tranquillity, or slow depression, during which tranquil 

 marine deposition was going on. 2. A period of vast internal force 

 manifested in the form of upheaval of land, and formation of lofty 

 mountains. 3. A period, not yet entirely over, of the same force 

 manifested in an outward, or volcanic form. 



In the case of Italy, which we have just considered, growth took 

 place around one long island or peninsula, and the first formed centre 

 seems not to have been subsequently depressed so as to allow de- 

 position unconformably upon it. When, however, we consider the 

 geological history of England, we find its case to be far otherwise. 

 Two centres of ossification seem from very early times to have been 

 established, both along the western margins of our present land, 

 and corresponding to the districts of Wales and Cumberland. In 

 Mid-Silurian times land clearly existed in Wales and adjacent parts, 

 though this early nucleus — as well as one which probably existed 

 in Cumberland at the same time — was soon depressed, and the 

 deposits of Upper Silurian age, which were first formed around, 

 gradually overlapped, and were formed upon the old land surface. 

 These original centres reappeared in a measure in Old Eed times, and 

 probably did not entirely disappear in Carboniferous times, at the 

 close of which they were again more fully developed. 



Through the Permian and Triassic periods the Welsh and Cum- 

 brian centres remained distinct and separate,^ while deposition was 



^ Etna dates clearly from the Pliocene period ; its earlier eruptions being sub- 

 marine, ashes and lavas interbedded with Pliocene strata. 



2 See " Geological Dream on Skiddaw," in " Ice," a Lecture, etc. 



