2 3 8 



HA RD WICKE ' S S CIENCE- G O SSIP. 



be parts of the series or to be intruded into it. In 

 other places they have been made to appear to 

 overlie much newer beds. A section across the 

 St. David's promontory shows an arch of Cambrian 

 rocks, and of Arenig beds containing great masses of 

 igneous rocks, probably portions of sheets in the 

 forms of Laccolites, all bent over a core of pre- 

 Cambrian rocks, and repeatedly broken on the west 

 side by thrust-movements, causing newer beds to be 

 driven over beds of various horizons, in some cases 

 many thousands of feet apart in the succession ; 

 whilst on the east side the limb is broken by reversed 

 faults, so as to make the beds appear to dip under 

 the pre-Cambrian rocks. Again, in the pre-Cambrian 

 core itself the Pebidian rocks are not only sheared 

 to an enormous extent, but are also made, on the 

 south side, by reversed faults, to appear to lie under 

 parts of the granitoid rocks (Dimetian) ; one result 

 of these mechanical movements being to make the 

 Dimetian look as if intruded into the Pebidian beds, 

 whilst in reality it is everywhere here bounded by 

 faults, as the result of repeated earth-movements in 

 pre-Cambrian and subsequent periods. The author 

 also showed that very similar results have taken place 

 in the sections between the Menai Straits and the 

 Snowdon district, where not only do the Cambrian 

 rocks appear to underlie the pre-Cambrian, but at 

 one point even Arenig beds are made to dip under 

 both. The author stated that in a section in Shrop- 

 shire, extending from the Longmynd across Caer 

 Caradoc, Lower Palaeozoic rocks are faulted so as to 

 appear to underlie the pre-Cambrian rocks of Caer 

 Caradoc ; whilst on the east of Caer Caradoc, as the 

 result of thrust-movements, great thicknesses of the 

 lower beds have been hidden by much newer ones. 

 He mentioned that the changes which have been 

 produced in the rocks themselves are also very 

 marked. The granitoid rocks give evidence of 

 having been greatly crushed by the earth-move- 

 ments in pre-Cambrian times, and in the lines of 

 fracture secondary minerals have been freely de- 

 posited. That these secondary minerals date back 

 to pre-Cambrian times is shown by the fact that 

 the pebbles of these granitoid rocks in the Cam- 

 brian conglomerates contain all the evidences of the 

 early crush with secondary minerals in the crush- 

 lines, in addition to those of subsequent fracture 

 and deformation by pressure after they had been 

 entombed in the conglomerates. Some of the fel- 

 stones in pre-Cambrian times were crushed so that 

 they were formed into felsitic schists, and fragments 

 of these schists occur frequently in the Cambrian 

 conglomerates. Various dykes in the pre-Cambrian 

 rocks exhibit indications of having suffered greatly 

 from mechanical pressure in pre-Cambrian times, the 

 diabase dykes in the Dimetian being frequently 

 cleaved so as to look almost like slates. Fragments 

 of these, and of many other cleaved and altered 

 rocks, occur frequently in the Cambrian conglome- 



rates. In the Cambrian and Ordovician rocks the 

 evidences of pressure during subsequent earth-move- 

 ments are also abundant, and secondary minerals 

 have been freely developed along planes of cleavage, 

 and in lines of fracture. The effects on some of 

 these rocks near thrust-planes are well exemplified 

 by the remarkably distorted condition of some of the 

 fossils. In Tremadoc beds, near St. David's, an 

 orthis, which in its normal condition was about seven 

 lines in width, was so distorted that it measured over 

 twenty-seven lines, and others were still further 

 drawn out so as to be almost unrecognizable. 



NOTES AND QUERIES. 



The Food of Birds. — Mr. Macpherson's notes 

 on the food of birds is very interesting. As to the ■ 

 bull-finch, if any one will examine one internally at 

 the time when the gooseberry is in bud, he will find 

 that it is partial not only to insects frequenting the 

 bushes but to the buds themselves. 



Black Mustard. — Last week I was at Torquay, 

 and noticed how fond linnets are of the seeds of the 

 black mustard [Sinapis nigra.) One would have 

 thought that they would have been too warm, but 

 they seem as fond of them as chaffinches are of 

 radish seed. — F. H. Arnold. 



Tenacity of life in a Cat. — A very severe 

 accident to a cat came under my notice about two 

 years ago. The cat was in the habit of catching 

 mice under a machine for lowering casks into a 

 brewery cellar. One evening it was working and 

 the first hogshead of ale was rolled on and lowered, 

 when it reached the bottom, the screams of an 

 animal attracted the attention of the man : he looked, 

 and found the cat was trapped between the edge of 

 the cage and the floor. She was caught across the 

 loins and had to remain in that position until he 

 called another man to help him upend the hogshead. 

 If he had rolled it off, it would have smashed the 

 cat to atoms, as its weight was about six cwt. 

 When the cat was released she crawled away and 

 they could not find her again that night. Next 

 morning she was found in the cellar alive, and 

 brought up to me. I examined her, and could not 

 find any bones broken, but she could hardly move. 

 I decided not to kill her, but try and bring her 

 round, so made a bed in a warm corner of the 

 engine-room ; she lay there for three or four days in 

 a very weak and bad state ; in about a week she had 

 three dead kittens, and then began to recover rapidly. 

 For a few weeks she could only limp a short distance 

 from her bed. She is still alive, and no one would 

 notice by her appearance that she had ever been so 

 badly hurt, since that time she has had about eight 

 kittens. She is very quick in all her movements, 

 and a very keen mouser. When I read the note on 

 the same subject in Science Gossip for July, I thought 

 the above might interest some of your readers. — 

 Jiw. E. Nowcrs, Burton-on-Trent. 



REDSTARTS in Winter. — The bird in question is 

 evidently a redstart, and is identical with the female 

 redstart that is familiar to us in our gardens during 

 the summer months. It is preserved and can be seen. 

 I could not think of the black redstart, when that 

 bird is recorded to have only visited the shores of 

 Britain about half a dozen times. The locality is 



