HARDWICKE'S SCIENCE-GOSSIP. 



99 



not to lean on the side of tenderness in dealing with 

 would-be intruders. An osprey was shot on the 

 coast last year. I saw it in the hands of a taxider- 

 mist at Lymington. Snipes and woodcocks remain 

 here in small numbers throughout the year, and their 

 eggs are found every season. Peewits breed in great 

 numbers among the bogs. During the months of 

 March and April the heronry at Vinney Ridge 

 presents an animated appearance. There on the top- 

 most branches of some of the tallest and finest 

 beeches in the forest the herons may be seen sitting 

 on their broad flat nests, or engaged in feeding their 

 young. The trunks of these splendid trees are four 

 or five feet in diameter, smooth and branchless up to 

 a height of some twenty feet, and one would suppose 

 the nests were inaccessible — even to the proverbial 

 nesting boy — yet many of the eggs are taken. For 

 this purpose large iron spikes are securely attached 

 to the legs, and the climber makes the ascent by 

 sticking these into the tree step by step : but it is 

 a perilous feat, and one which requires a steady nerve 

 and a cool head. The herons always lay twice and 

 frequently three times in each season, beginning 

 early : by the second week in April the young are 

 already half grown. In May or June they leave their 

 nesting haunts and retire to the coast. I have seen 

 three of the woodpeckers : the green, the greater 

 spotted, and lesser spotted, but the first is by far the 

 most common, indeed, although the shrill squeak- 

 ing laugh-like note of the two last is not an un- 

 familiar sound it is not often that the birds them- 

 selves are seen. Nut-hatches are pretty common 

 and are known by the euphonious name of "mud 

 dabbers " from their habit of plastering mud around 

 the holes which lead to their nests. Kingfishers are 

 scarce, and I have rarely seen two at once. Speak- 

 ing of these birds, perhaps it is not generally known 

 that they can and do procure their food from the 

 sea as well as fresh water. I recollect observing 

 this in Sark, one of the Channel Islands, where king- 

 fishers are numerous, though there is not in the 

 island a stream or (with one exception, I think) a 

 pond big enough to sustain a minnow. More than 

 once I have seen them among the rocks at low tide. 

 The wryneck arrives here about the 1st or 2nd of 

 April, and the cuckoo about the 20th. Nightingales 

 are very plentiful, and usually begin to sing towards 

 the middle of April. Swallows, house and sand 

 martins arrive the second or third week in April, and 

 swifts during the first days of May. Our latest 

 summer visitant is the night-jar, which begins its 

 singular churring note usually on the 16th or 17th of 

 May ; last year however I heard one as early as the 

 7 th. These birds breed commonly on heaths, and 

 lay their eggs — never more than two — on the bare 

 ground. On one occasion I found a pair of night- 

 jar's eggs as late as the 5th of August, this I noted in 

 Science-Gossip, vol. xiii. p. 259. 



{To be continued.) 



SKETCH OF THE GEOLOGY OF CARDIFF 

 AND SURROUNDING DISTRICT. 



TO those interested in geological pursuits there 

 are few localities possessing so many advantages 

 and at the same time offering such a varied field 

 for research, as the neighbourhood of Cardiff. Such 

 being the case, a brief outline of the leading features 

 of the district may not prove uninteresting to some of 

 your readers. 



The town of Cardiff is built upon the western 

 portion of a large plain, the surface of which is not 

 much above high-water mark, in fact, some parts of 

 the surrounding moors are periodically covered with 

 tidal water at the vernal and autumnal equinoxes ; geo- 

 logically speaking, it cannot have been long since 

 the waters of the Severn flowed regularly over, and 

 indeed far inland, to where Cardiff now stands. 

 The surface soil consists of a foot or two of stiff clay, 

 resting upon rolled blocks and pebbles brought by 

 the action of water from the older rocks of the 

 district ; these in turn rest upon the Keuper marl of 

 the Triassic formation. 



Cardiff boasts the possession of splendid dock 

 accommodation, and is visited by the mercantile 

 fleets of all nations for that important article of 

 commerce, steam coal, for which South Wales is 

 justly famous. 



The geological map of Great Britain defines a 

 large district in the neighbourhood of Cardiff as being 

 occupied by Old Red Sandstone deposits. This to a 

 great extent is correct, but a careful re-survey of the 

 district would very materially alter the boundary of 

 this formation, and cause the introduction of a con- 

 siderable tract of Silurian to be substituted. It is to 

 be hoped these alterations will be made at no ve;y 

 distant period." 



The Silurian deposits are well exhibited in a section 

 on the river Rumney, about two miles from Cardiff, 

 where a total thickness of rock exceeding 700 feet is 

 exposed. These beds are replete with the customary 

 fossils of the upper or Ludlow series, and at present 

 it is a moot point whether deposits representative of 

 the Wenlock series may not also exist here. 



The only rising ground of any importance in the 

 immediate neighbourhood of Cardiff is Pen-y-lan. 

 This is a low hill composed entirely of Silurian 

 deposits ; a small quarry nearly at the top of the 

 hill has furnished the writer with a typical collection 

 of the interesting fossils of this formation. This spot 

 will repay the visitor for the walk, as a commanding 

 view of the British Channel, the flat and steep 

 Holmes, the coast of Somersetshire, and the Liassic 

 plateau of Penarth, and Leckwith can be obtained 

 from here. 



From the Silurian to the Lias represents an enor- 

 mous thickness of deposits, yet, if we except the 

 Permian and Lower Lias, the entire sequence may 

 be obtained within a radius of about a dozen miles 



F 2 



