Jss. 9, 1685.] 



♦ KNOWLEDGE 



23 



quartzo-e slat*"?, and whitish slates and grits. Thi-se occur 

 at the northern end of the Foi'est, httween Charley and 

 Blackbrook. At Whittle Hill, too, the tlinly slate which 

 is worked fcr hones (and these " Charley Forest ' oil- 

 stODes are to be found in joiners' shops all over Britain) is 

 probably of the same age. 



TfiiAS 



SAnosTonc 



SVtNITE 



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Fig. 2. — Section across Charnwood Forest (diagrammatic). 



2. Banded Slates, with volcanic breccias and (in the 

 uorth-west) immense agglomerate.^. In the upper part of 

 this division are pebble-beds and grits : a bed ol quartz-grit 

 forms the top. The banded slates are very characteiistic ; 

 they consist of alternate layers of fine and of coarse sedi- 

 ment, the finer layers weathering white. By the dille- 

 rence in colour and texture of the bands it is ea.sy to 

 ascertain the dip or slant of the strata. Such beds are finely 

 .shown along the eastern side of Charnwood, at Nanpantan 

 Hill, near Loughborough, the Hanging Rocks of Woodhou.se 

 Eaves, and further south round Roet;liir Hall, Holgate Hill, 

 and Old John Hill. On the western side they are not so 

 common, though there is a t\ pical exposure at Billabarrow 

 Hill. The quartz grit-bed which lies at the top of this 

 division is shown in the Stable Quarry in Bradgate Park, 

 near the boat-liouse of Groby Pool, and in a little quarry 

 at Steward's Hay Spring. But the most remarkable beds 

 are the wonderful volcanic agglomerates which lie between 

 Bardon Hill and tie Monastery. This north-west corner of 

 Charnwood seems to have been the site of the volcanic cones 

 from which the ashes were ejected which form so large a 

 portion of the Forest Bocks', and h( re, accordingly, the 

 ejected blocks are largest and most frequent. Great piles 

 of volcanic bombs lie heaped together, marking, perhaps, 

 the proximity of the "necks " up which the fluid materials 

 rose ; such collections of blocks are termed agglomerates. 



Bardon Hill is an outlying mass, Sf-parated from the 

 surrounding strata by lines of fault, of the same beds of 

 volcanic ash w hich form Green Hill and Peldar Tor. There 

 is a peculiar bed of ash which occurs at all these points 

 and renders their identification possible. It cont.iins 

 numerous crystals (sometimes broken) of felspar, and 

 rounded grains of quartz which stand out like peas on the 

 weathered surfaces of the rock. I have found the same 

 stratum in Birchwood Plantation. The crystals were not 

 formed ni liitu, but were showered out, with all the other 

 matter, from old cones and craters. 



3. The highest beds of Charnwood occupy — as is 

 frequently the case — the lowest elevations. They are 

 fine-grained greenish-blue and purple slatfs, which are 

 largely quarried at Groby on the south, and at 

 Switldand on the south-east Underneath newer rocks 

 they doubtless extend for a considerable distance ; but 

 they are only brought up again at one spot, viz , 

 to form a kno 1 in Brazil Wood, which lies half-way 

 between Swithland and Mounfaorrel. Here Mr. Allport 

 and myself were fortunate enough to discover the junction 

 with the granite. The latter rock has pushed its way 

 through the slate, sending long tongues into it and altering 

 it into a micaceous schist, which is crowded with garnets. 



A liitle study in the field of the three seta of 

 strata we have now described will show that they 

 are usually inclined at rather high angles — thirty to 

 sixty degrees — tj the horizon. All along the eastern 



side of the forest the various beds dip steadily to 

 the ea'st. But as we approach the southern end 

 the direction of the slant changes — in Bradgate Park — -to 

 south-east and south, and ultimately it sweeps right round 

 to the wesf, in which direction the strata are inclined all 

 along the western side, from Marktield to the Monastery, 

 and beyond. From this opposing ilip of the rocks on the 

 opposite sides of Charnwood, it is clear that there must be 

 a point, somewhere between, where the dip changes ; such 

 a point is called an ((uticlinctl, and the anticlinal line 

 separating the strata which dip eabt from those which dip 

 west can be tract d running from north-west to south- 

 east, right from White Horse Wood, by Lubcloud and 

 Bawdon Castle, down Ling Dale to Holgate Lodge. 

 This anticlinal line runs along a valley, and not, as 

 some might expect, along a ridge. The fact is that along 

 such ar. axis the beds are weakened by the strain, and they 

 crack and lis>ure ; the agr^ncies of denudation avail them- 

 selves of the oppoi tunity, and soon the rocks along the 

 " anticline" are eroded and a valley is formed (Fig. 2). 



Sub.icquent earth-movements have, in the case of 

 Chainwood, converted the anticlinal line into a line of 

 fault also. The beds have been there cracked, and the 

 strata on the eastern side have slipped down at least 

 500 ft. Yet no precipice of .'"lOO ft. altitude divides the 

 eastern half of the Forest from the western. For again 

 the levelling agencies of rain and frost and ice have 

 acted most on the most elevated portion (the western 

 half), and reduced the whole to tolerable evenness. It 

 is most interesting to find, as the geological surveyors 

 have recently done in the " rainless " tracts of the western 

 part of the United States, faults really marked by terraces 

 many miles in length ; but here, in England, the geolcgsi 

 gets no such indications of "growing faults." 



In seeking for the conditions under which the stratified 

 rocks of Cliainwood were dipo^ited, we must study modern 

 volcanic districts, and in the Plilegr;ean fields, west of Naples, 

 we have a scene probably not much unlike that presented 

 by Charnwood many millions of years ago. Here numerous 

 small cones have ejected enormous quantities of scoria-, 

 lapilli, and dust-, which form a well-stratified flepo.sit of 

 considerable thickness, covering many square miles. Such 

 was probably the state of the Charnwood area in Pre- 

 C'ambrian times. The erujitions took place chiefly in the 

 nortli-westeni corner, near Whitwick, where several cratns 

 must Lave discharged steam and ashes. " The lowness of 

 the hills and porosity of their materials would be unfavour- 

 able to rivers ; the ash would settle down in the quiet 

 waters of lakes or lagoons, little rolled, or be spread out 

 upon the jilain." As to the absence of fossils, we know 

 that the organic nature of the only su|iposed Pre Cam- 

 brian fossil — the famous Eozoon — is now strongly ques- 

 tioned, so that their absence in the Pre Cambrian slates 

 of Charnwood need not surprise us ; but, in addition, it 

 is plain that the continual showers of hot ashes from the 

 volcanoes then in action here would be inimical to life, 

 whether on the neighbouring land or in the waters. 

 (To be continued.) 



There lies before us a record of the splendid services rendered, 

 and the gallant rescues effected, by the boats of the Royal National 

 Lifeboat Institution durin;^ the year which has just closed. From 

 it we gather that 7S0 lives have been saved through the instru- 

 mentality of the Society during the past twelve months, and 31,:ii:i 

 since its foundation. In order to carry on this great work, which 

 is second to none in importance, and to maintain in eflBciency their 

 fleet ol 284 boats, the committee maVe a strong appeal to the 

 public for help, feeling assured that that appeal will not be mado 

 in rain. Contributions are received by all the London and Country 

 Bankers, and by the Secretary, Charles Dibdin, Esq., 14, John- 

 street, Adelphi, \V. 



