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THE 
 
 QUEBEC LAND SLIDE 
 
 OF 1889, 
 
 BV 
 
 C. HAILLARGE, M. Can. Soc. C. !•: 
 
 FROM TRANSACTIONS OK 
 
 Wp Qimnhm ^iSatiahi of (Biuil Jlnginri^rs. 
 
 Vol. VII— Part I, 
 
 (■lANY. TO .IHSB. IH!U.) 
 
 1893. 
 
2- igoi. 
 
Tliiii'Mlay, 4tli May. 
 K. I*. TJannaPhru, Prcsidonr. in the Cliair. 
 raper Xo- 7tf- 
 
 TllK QUE15KC LAND SLIDK OF SEl'THMBER 19, 1889. 
 My (has. Baillaiuoe, M.Caii.Soc.CE. 
 
 In 1879 and for years {)a:-t tliere had existed dangerous fissures in 
 tlie cliff opposite tlie King's Bastion of the Gitadtil, Quebec. The 
 attention of the Federal (jioveinuient having been ealled to the alarm- 
 ing aspect ol thcH; " ercv;\<.ses," the author wiis instructed by Sir H. 
 Ijaegevin, then Mini.ster of Pubiii- Works, to make a survey of tLe 
 locality ami report thereon, '•, itli such sugircsfcions as nii'jlit be deemed 
 advisable in the premises. 
 
 Plates IV and V, together with a vertical section of the cliff at each 
 of the proposed buttresses, were prepared at that time and sent in with 
 tin! author's report m January, 1H8(), with thee.Kccptiou, of course, that 
 as the accident had not tiien occurred, it did not appear in Plate IV, as 
 since indicated as eompriseit 'vithin the area A B C D E F G, and the 
 line to whicli the debris weie projected, I's shown, on tlie opposite side 
 of tiie road'v.iy. 
 
 I'late IV is a \Am\ v.y bird's eye view of a portion of the Citadel and 
 Glacis, the soulli-westei 11 extreniiiy of Dnffesiii Terrace, and that part 
 of Cimmplain stieet overtaken by the -.valaiiche, or which was likely to 
 be in e;i,se oi' iin eventuality. 
 
 I: late V is an elevation or fioiiL view ol' the cliff, etc., showini: the out- 
 crops of the almost verticil strata of the lace oi the clilf. as shown in 
 Plate VI. 
 
 The conclusions of the authorV report were that, should the rock give 
 way, it would take tlie iiouscs on both sides of Chainplaiu .'>treet, and 
 that they must either be vaeattul^or a series of buttresses erected to 
 Btay the danger. 
 
 The rock being at the time in a state of stable equilibrium, and the 
 
•2 TIlc Qucht'c Lund SliiJc. 
 
 jiortidii oi' it wliifli lias >\nw fallen not ••xeucdin.: 36,000 tons, the 
 ftourt>o;iti' count; raeting weight of tlio buttrcssus bciug sunio 12,000 
 tons, would, no (Imiht. have provuil etfeetive for many yojirs to 
 come; but as the author laid greater stroi^s on tlie recomineiidation to 
 have (he premises vacated, as tlie surer mode ol' conjuring the evil to 
 be apprcheudel, the Government engineers jidvised tlie purchase of the 
 property at the foot of the clitf and its deniolition, as being also the 
 cheaper alternative. 
 
 This suggestion was carried out, and a wall a l> c il t on plan and w on 
 section was erected, increasing the width of street by eight feet, and 
 to answer as a screen or fender to [ire vent falling stones from rolling 
 over to the opposite side of the street, and thus possibly avoiding acci- 
 dent to life, limb or property. 
 
 It is, of course, to be regretted that the projierty on t!ie river side of 
 Champlain street, at the siteof ti.e accident, was not also bought up and 
 demolis'iied (or, as Major MMyne suggests, the houses vacated, but loft 
 standing and tilled in as a screen against falling debris), since, in the 
 author's report, ho repeated the warning that " wlun the clitf falls, it 
 will be sure to destroy the property on both sides ol' the street." 
 
 There is another point in which both the phm and elevation now 
 submitted difl'or from the originals of IS^^^O ; to wit: the iudieatiou 
 theroon of the drain which from the King's Bastion runs along the foot 
 of the rip-rap faeing of the lower glacis, and thence under the Terrace 
 flooring and through the wall as shown, towards ChaMiplaiu street and 
 the river; the existence of this drain being unsuspected at the time the 
 plans were made. 
 
 Keferring now to the following conclusions as to how the slide occurred, 
 it will be understood that V I) E is the line of outer crevasse along which 
 the cliff parted, A B C D E F G that portion of the clitf which was forced 
 out and tell over, the debris rcachiiig, as shown on plan aud seciiou, to 
 about 40 feet on the river side ol Champlain street. 
 
 The crevasse in Jcated on plan aud elevation as "present crevasse" 
 is the one now existing, into which the water poured from the broken 
 drain at J), tilled (he crevasse as hereinafter described, Ibrced out the 
 rock between the two tissures, and caused the portion beyond C D E to 
 fall forward. 
 
 lutermediaiy tissures, not at tirst shown on plan, or uot then known 
 to exist, are now sketched iu and shown on section, giving the strata 
 their present fan-like, diverging or radiating appearance, and account- 
 ing for the fact, that while the present inner aud main crevasse is almost. 
 
The Qncher, Du^d Slide. 3 
 
 vertical and, in fact, inclining towards the left or westward, rJie outer 
 crevasse leans over or inclines towards ilie right or eastward l)y not 
 less llian 1 in 10. 
 
 The (Quebec rock is, geologically, of tlic Utica slate formation, and, 
 like other sedimentary strata, originally more or less horizontal. The 
 subsequent tilting up of the strata to almost verticality is, one need 
 hardly be reminded, due to the puckering, folding of the earth's crust 
 under the seismic effects of contraction of the interior nucleus in cool- 
 ing, and the outcrop of the strata to still subsequent erosion and wear- 
 ing away of the upper portions of the folds by the hand of time. 
 
 There appeared in the Canadian Architect and Builder for October, 
 1889, a section of tiie cliff and description of the Quebec land slide of 
 19th September, 1889. The author had not at that time reduced the 
 accident to calculation, nor had lie then the necessary data so to do. 
 Since then he has had to work up the case for the Exchequer Court 
 and give evidence as to how the fall of the cliff was brought about- 
 Having visited the Citadel ditches, he found that the whole ground 
 fell some 40 ft. in level from the western to the eastern end; that the 
 area, including roofs of casemates, draining towards the King's Bastion 
 just opposite the centre of the avalanche of rock, was such that, into 
 the depth of rainfall for the 12 hours immediately preceding the acci- 
 dent, it gave some oO,000 cubic feet of water, the average of rain and 
 melted snow per annum for the last twenty years being 24".0G of rain 
 and 15".45 of melted snow — a foot of snow being assumed equal to an inch 
 of rain — or (iver one-quarter oi' a million cul)io ft. per annum which had 
 been pouring down the eliff i'or years past, instead of finding its 
 natural outlet towards the river through the drain already alluded to 
 which liad probably been built for 60 years or more, but which tlie 
 author found to be completely choked with earth and nibbisli, and so 
 solidly packed that not a drop of water could find its way through it. 
 
 This drain, some 20' in diameter, though uselessly large for the duty 
 it had to perform, was found to be burst or broken just below the 
 King's Bastion already alluded to and immediately to the eastward of 
 the stairs reaching from the Terrace to the Citadtd. The aperture in 
 the drain was just above the point at which it was so completely 
 choked as not to allow of the water getting any further, so that all 
 the water found its way directly into the fissure which now exists 
 and has existed for years in rear of the Terrace, and, as already stated, 
 opposite the very centre of the land slide. 
 
 Keferriug to Plate VII at ^1 on plan and at A 1) (J on section 
 
4 The Quebec Land ^Ude. 
 
 is the present crevasse or fissure into which tlie water poured unA 
 has been pouring for maybe 30 years past, or ever since the drain, 
 which ran north-eastward down the cliff towards the river, ceased (o 
 be operative, as evidenced by the author from the fact that from its 
 outcrop hall' way down the cliff no water had boen runnin<r for fully 
 that number of years. 
 
 This fissure has existed for Ioniser thim anyone now can remember, 
 and there is no dmibt that the drain was built to prevent I lie Citadel 
 ditch water from finding its way into it and thus hastening a land slide ; 
 but the drain seems to have been, in after years, entirely forgotten or 
 paid no attention to, and nearly all that portion of it north-eastwanl 
 of the break in the side of the brick barrelled portion of its oontinun- 
 tion up the cliff being a mere deeply imbedded surface drain, it soon 
 became filled in by the fall of the crumbling face of the shaly rip-rap 
 work of tiie glacis front above it, dust and vegetiible growth. 
 
 This fissure .1 up to the time of the accident had been mostly 
 hidden from view by debris from above fallen into it at its outcrop, and 
 public attention was concentrated on, and tliat of the Government called 
 tOj the alarming appearance of the fissure at 7>, wlierc the rock gave way 
 at Ihc south-western end of Dufferin Terrace. 
 
 As already stated, the author was calleil by the Federal Government, 
 ill the year 1880, to repiu't, when ho said that if the rock fell it would 
 take the houses on both sides of Chaniplaiii street, and recommended 
 the erection of a series of buttresses of heavy masonry some 6 ft. thick. 
 50 or more (t. in depth between the roadway and the elift', and some 8n 
 ft. in height, and rising, .say, to /''. The cliff", or tlu; portion of it E /> 
 F G which fell, being, like the leaning tower of Pisa, though in(;lined, 
 in a state of perfectly stable I'quilibriuni, and such that the buttresses 
 ])roposed, and which were to iiavc been erected at distances of about 40- 
 ft. apart — seven of them in the oOO It. from // to K on plan — must 
 and would have proved effective in staying the catastrophe. Major 
 Maync's advice, who, as stated, had recommended that tlie range of 
 liouses at the foot of tlie cliff after ii< ing vacated be allowed to remain, 
 was disregarded, or at least their gable end walls, which, abutting or 
 nearly so, as they did, against the rock, might have so broken or checked 
 the I'all as to prevent the debris from rolling to the opposite side d' 
 Champlain street, and there destroying the houses which, heedless of the 
 author's written warning that the rock in falling would sweep away the 
 residences as well on the river as on the cliff side of the street, had been 
 allowed to stand, and in the destruction of which more than 50 persons- 
 lost their lives. 
 
The <^iirh,r L,nul Si:.(/e. 5 
 
 Much moroapprolicusion was folt about the craok ;it B tliaii that at 
 A, aii'l the (jtoveruiueiit caused the upper portion of it for soiiie feet 
 below tiie outcrop to be filled in witli coucretc, with the idea of prevent- 
 iiit' water from above from reaehiii'' and fallin"; into it, wliicli it wa8 
 supposed, actiiij:' both by its disint'jgratiiig power and by swelling 
 under tiie effect of frost, miglit gradiuilly overtiu'ow that portion of the 
 eliflF which has since f-iUen. This was a very foolisli tiling to do, as will 
 soon be made apparent ; for first of all, no water from the Citadel 
 drainage above could re;ich the lissiiie, since it must on Its way be inter- 
 eepted by and enter the crevas-o A ; and secondly, by bringing about 
 a contact between the opposite faces of the cracl: at B, whicli were some 
 two or inoie feet apart, any shock or push from the rear must inevitably 
 thrust forward that portion oi' the cliff to the right of B (as you took 
 at the section), and hasten its destruction. 
 
 ^'l is the crack, if any, which .should have been filled in; but, being 
 liardly noticeable to the untutored eye, and so remote from B or F, was 
 not suspected of any foul intent. 
 
 T lie author had the crevasse .l gv^ie into and sounded to a depth of 
 more than 70 ft. below the surf\xce, or to iVon section; and as at th^'t 
 depth there was still the breadth of a man's body, it was made evidi . ' 
 by ■' similar triangles " that the total depth of the crack was 125 ft. be'ow 
 A and 109 ft. at D — the general level of the rock and earth beneath 
 the terrace flooring — and to which level D any water filling the cre- 
 vasse from C could rise without any possible issue below said level D. 
 
 Professor Laflamme of the Laval University, (li'olagist, in his evid- 
 ence before the court, stated that he did not know enough of the cliff 
 to lead him to infer that the fissure C A could fill with water, as, from 
 the very broken and disintegrated appearance of the rock as ssen along 
 t!hamplain street, one would certainly be leil to infer that if such 
 disintegration and looseness of structure extcu le 1 to tlie interior, any 
 water pouring into A must leak out from below as last as it entered 
 from above ; but it so happened that having .so n and examined this 
 elitVever since the land slide of 1841, in view of th' likeliiiood of a 
 recurrence of such an avalanche, and more especially ilming tiie last 
 20 years, the author knows it to h' a fact that the wat 'r from the 
 fissure could only find its way out of it by a very slow process of filtra- 
 tion through the intervening space of over a Iiundred feet between the 
 crevasse and the face of cliff at /' G, 
 
 The author repeatedly watched the w;iter running fiom out the foot 
 
ofciift" ;ii'ti!r licavy rains, and p;ii'ticularl_y while siirvyiiii: tiu' ciiffin 
 rear of the limiscs lor liis rcjidit ol I SSI), and iiovcr saw aiiytliiiiLr iiioro 
 all aloii::- uihI Ijcvdiid tl'.c ."{OO It. ol' inck IVoiitaL'e toward- tlic St. 
 l/iwu'iicr than a lucre trieklinu oi'j tl:i' uati i- liom ilie lii'uvaixe 
 tissiii'e.s and others to lie sern. ami it alway- tnnk si\i lid days al'tir 
 raeh fall ot' rain lielori' the slowly running wat' r Ironi the lis-<ures 
 eeasi'd. showiiii: that the crevas-e ^1 wmild cv eiitiially Ixconie eleai" 
 111' wall !•, hiit hy an cxtrenii'U siow ]iroces-. 
 
 And 1 ven at this time, when the (Voni rork has I'all'n away IVuni 
 />'. a'.d le'iv.'~ ill" f'aee /',/' e\]i0srd, 1 1 e^'los. m s< of tin' roni|i(ini'nT 
 til nit Mts is anyihini: but enniiueive to il e \ icw thai vvatrr llMwin- into .1 
 wonid flow out litun below as la-I as it passeil in at tup; and il'llK'I'aee 
 iifthi' rlitl'as ui w "XiMiscd at li/' i^ a lit lie -haky or nt appari'mly loose 
 sirurtur.-, thai is no reason to inhr tliat at lit' lo 70 ft. in llic interior 
 of ll;i' monntaiii. and wliav So far reiU'iVrd iVnin atnio>|ihi'iii' and 
 di>int' Liratin^ inHnenco. the tt xture of the separate >lr;ita i.- anythiuu 
 like a- l(iii>e, il' loo.-if at all, as the view at /(/'woidd lead •■ne to infer. 
 
 The component strata of lie' e'.ilF just alludeil tn. whieli llieseetion 
 show.- to be vertical or nearly -o, havinu, of course, been tilted up from 
 thrir oi'i-inaily more oriels bori/ontal ] o-ition iiy an uplil'iiiii:,' llircc 
 I'rom beneath the earth's crust, .similar to tint which on a smaller .sotdo 
 throws the eruHt of ti sea pie into bills and rid'^rs by the t .\pandin^ 
 forces (d' the imprisoned vapours utiderne.ith, or, as iK'olo'jists also 
 ineliui' to think, by the pnekerini: eth et on the eartli'- irii>t of lateral 
 pr-'^-un due to the contraction of the snrfacf incident on the coolinj; 
 down ol tlie interior, suh.sctjnent crosimi and denudation of the apieo 
 of the folds leaditii:' ti the outcrops nciw visible at tlie surface (ui a 
 bird's eye view thereof. 
 
 in the section of the <-litl' piihii-heil, a< already ~t it' d, in the 
 (' iHitd'nni Aicliih'if iiiid /liii/i/ir \\\ l.-'Sif or >lioit ly after the accitb'iit, 
 all the ,>itratu are shown parallel and leaning lUtwards from the V(M'ti- 
 cal; but a closer Mtrvey and .■lelual mea-urement>^, levellini;s and 
 plumbiie.js have disclosed the fact testilicd to by the autlmr bid'inc 
 .hidjie IJurbriduc, that the inclination outward or overlian'.:ini; at /»' is 
 t'l ft. in the I'lO fi. from /.' to /'. ny 1 in 111, while at .'.| ami on jilan 
 iMate VII, the stratti imlim^ inwards jir-t a.- tliey do at J on plan and 
 flection. Tlie author was for some time at ii lo.s.-i lo account iiu' this, 
 until, after diii::in'j away lie overlyimr earth, he discovereij a .series of 
 crevice- between .1 and /ion plan ami siclioii, v.iryiit'J in uiillli at the 
 
TIk i}il,'},rc L.IU'l Sinh', 7 
 
 outcrop IVoiu IV' to 2 ' ;in<l 4 uml >' . td ;is much a,- 11 • and 20" us 
 seen on scitiou. and wliidi t'i'lly a(,'i'caiiits iiir the pivsiut iionparalli'lisiu 
 oftlio sirata. 
 
 ('(iiiiiiii:' now tc llie arlual sulutioa uf ilic pididcm as lo ilic hvili-'i- 
 :-;tatic power nt'ilic water to liriiii; about tht; acciili'iit, t'le lollowinu aiv 
 the flat I ■ The cn'vasso at .1 ixtdiils ami can lio t'ollownl for 150 fr. 
 or more IVniu .1 to O on jihiii. wlh iv it ihiii< out i ithini:'. In th^' op- 
 posit,' dirretioii, or tVoui .1 to .1/, it is al-o a-siiiiiiMl |o clos" or l'o:uo to 
 u.'- i>'!,t at a likr distaucc of loOtV., to-rtlirr ;;00 ft., and this assump- 
 tion is ia-rd on th" t'ict that the eTa(.'k: wa> uoui' into in tliat direction 
 to say 70 It. from .1 towards .)/, audits hrcadth :it llial point stidi — 
 tliatof'a man's Imdy — a^ to warrant the a^-umptii m. 
 
 1 1 has airoady been said lliat thi' drpih df (-revassi' is I'rom f) '.<> ^""oii 
 .-tction lOn It. At .1, til',' outcrop, the aniplituli' of crack is now .'{.V 
 ft. and at />. :\ ft.; hut Indbre theaccid.'iit occurred it was but 2.V ft. at 
 /''or."! it. ,i( .1, the ereva--e having opinii !)y xmie li inch's ,it its 
 centre of jiuMtion or at .1 .nj plan and -ct'on at tlie time of th" cat i- 
 Iroph,'. Xtiw. ■_", ft. al /' and n.ni-ht al C uives 15 inches at ,V. 
 Auain. tlitse 1.') inehrs 'I A' or hall way down bcui'atli A on phin. and as 
 tlie era Iv dii - laii at J/ and O. -ive a uvneral avcra-v ol' 7', inoiieg 
 for the breadth o|- widtli or antplilnde uf (be crevasse. 
 
 The face of the crevasse is. as already infiTred. ;!(lil -.niA luu It., ,.r 
 .'iO.lKMI ,Mpniie ft., and the average breailth bcin- 71 imdi.s, uivcs i7.r)tlO 
 cul)ic feet tMpaeiiy. or say from 1 a,! 100 to 'JO.dOO cubic ft. 'I'lic .'ID.- 
 <lil(t euliie I'l, of rainl'ad. whi -h durin- the liJ luHirs, m- from S a.m. to 
 S p.m. ol til.' IMlh Sejit.. |S^:t. precipit it.'d itself thron^li tb' ^id'' 
 apertnre in the drain, .iii'l whu'li i< in aliout th ■ sum : vcrtii;al iii.uv 
 as .1 /.'on plan and seciidii. found iis way int.i this cr.'Vissi' and tilled 
 it np to /> (the -pare lo OHH to Ili.OOO beimi' nior,' than ahuifhintly 
 -uflicienl lo allow for aii_\ le;iiva;j;c o\il at lb" l)ottom o: sides as it ■•• ■ 
 torcd at the top), e\erci-in,ii therehire nn lis opjiosite "aces a ^•epar.itiuLr 
 L'tforl of not les- than ti,^.")!! li)s per sipnre ft. at (\ d.ltid,^ jlis. at thi- 
 cmtre ofpre-^nre. nr \ up from ('. :',.V27) lbs, at the I'lUtre ofuravity 
 ol the liuuic. m- h ill' wa\ up, the Ij'^nri- bein'.: a paralli lonrani. and a 
 
 lotal thrust on the whole surlai f lii.ST."! tuns. 
 
 Now, the (diir tie| wi'i'ii .1 and /.'on phm and s,.cti,iii is, a- alrcadv 
 said, ."»llO ft, in Icu'^lh, and it I,- an .avera'.:!' (d' 05 ft. in lireadth or tliiok- 
 mss Irom .\ to //an I an averai;'' liei-li* uf .^5 ft., the hciL'iil decreas- 
 iii'.: towaid- A' on plan. 'I'he-' ii'.:urcs -ive 1 ,057,500 cubie ft f,,r liie 
 p(Htion of the elill which wa- iln-n-l forward a'.^ain-t the ro.d^ /'/.'/', 
 
8 The Quebec Laml Slhh. 
 
 and caused it to topple over; but it .still remuiiis for tlic author to 
 show that the hydrostatic pressure of tho watt'r iu the erack D C 
 fould produce this (itfect. Tiie weii;ht pi:r cubic foot of one spccinjoa 
 of gelid stone from (he debris of the eliff bcinj:, as weiL'lv d in water, 
 IGO lbs., wliile aiiotlier spet-iiueii liave 152 lbs., an average of loli, or 
 within a lb. (jf that given by the author iu 18UG. This, as just stated, 
 is for solid stune ; but the debris at the site of slide .show that there is a 
 large proportion of rotten shale and earth variously e.stiuiated at from 
 20 to 33 per cent, of tiie whoh". Taking this at only 2(lprreent. to be 
 on the safe side, and this earthy urslialy matter at 100 lbs., n^duees the 
 average weiglit of the eliff to, say, 145 lbs. to tiie eubie it. Another 
 way of arriving at this same average weight of tl^' still persistent clitt' 
 is the allowance to be made U'y the eartii infiltratt d and mostly empty 
 tissure-J between .1 and 7> on plan nid section. 
 
 T'he cubic feet of eliff whieii w;i- thru.st I'urward, and which pushed 
 over the rock beyond B, is l.(i')7.r)tifl ; this into 1-15 lb.s, average per 
 cubic ft. gives 240,:537,500 lbs. or 120.1 <i!l ton>. 
 
 Now, had the lock .1 ]> (! J'J on section, or II M A' on plan been 
 a solid monolithic block of stone, and suppo^'ing it even to be deti.iied 
 or nonadhennt at its base (' /'J, but subject to the friction there due 
 to its weight, and ineapatile of moving ibrwaid along (' K. or of start- 
 ing to move forward, under a le.>-< force ilian .71 <il' its own weiglit (the 
 coeiBeient of friction of dry stmi;' u* re^-t on dry >tone on a horizontal 
 plane; if unob,'<tructed. but which it could not do in this case, bi'eau>e 
 ob.structed by a weigbl of cliff beyond it much more than e(|uivaleut to 
 the remaining -o of its said wiMght : the .-^tnss against the rock at .1 C 
 could, had it bem a single hiiniogeneons mass, have acted only in a 
 way In inin or toiijile it over, by eausing it to rotal(> on its outer edge 
 at 7:. The force to 1k' exerted Ity ilie water to do this must Inve been 
 c<(Uivaleni to ball' ilie weight of eliff or to ti(),(IS4^ tons, while, a-> 
 already shown, the toi.il liyilio-t itic iressure exerted did nut exceed 
 4t>,S75 tons or less by nvrr 2> per cent, than the Inice re((nired In lift 
 the cliff at <.'aiid eaiit it forward at />'. 
 
 Iliit as alr(.'ady >eeii, the clitl i> not a hoinog' neons m.is>. and un (In; 
 contrary the .-ecliim .-linw- ii tn be llinnnighly di\ide(l iii'u niMrly \er- 
 tical and p.irallel stia'a ranjiuu liom a I'eW iiirh - tn srvenil lectin 
 thickness; ;ind llie.-c r-\.\:\\.[ are again divided liy plaiiCN of cleavage, 
 us indicated by the line* drawn obliipiely aero>-< tiie .^trata* into 
 
 '.' 'I'liei't' lliu'i' liiilli'iiti'il in llii' nil'.Miiiil -lieii'liisiu- iii;nMwcri|it li;ivc lirin iindvtMli'iiUf 
 i^noi'''! I y till' i'ii({r.i\ 11 . 
 
The Qiiehec Land Slide. 9 
 
 layers lying in a uinre or less horizontal Jircctidii fioiii ca>t tn west 
 along the River front. The angles of the planes of cleavage, of which 
 tlic author measured several among tiic fallen debris, varied between 
 17 and 23 degrees, — an average of 20. 
 
 Tlic j)laiK'S of cleavage, thert'forc. liad I lie .-(rata been vertical at 
 /> Z*', would have inclined some 20'' from the lion'z<aital, or -ay 1 in 3; 
 but it has already been shown that the inclination ontw.ird at />' /t-'is 1 in 
 10 oranotliiT 7 deurees. together 27^\ an inclination of 1 in 2, and such 
 that just one-half the Ibrcc need be exerted to thrust tite rock forward 
 as would iiave to be exerted on a horizontal plane. 
 
 As stated incidentally, the eo efficient of friction of ~toi;e on -tone at 
 rest is .71 *in a horizontal plane, wherefore, to start the cliff at /> and 
 tlown to P, where unlike at E it had lilierty to move forward or 
 through a portion of the vacant or [lartiy earth 'iil'"l and therelbrc 
 eomprcf:sible and reducible space in the (diasm li />', would have 
 required .7 of its weight or of the 120.1fi9 tons weight of cliff />' C, 
 say 84,118.8 tons, wiiieh the hydro.-tati' prcssun' eouM not have done 
 had the jilancs of cleavage or of motion been parallel to the horizon ; but 
 on an inclination of 27', or of 1 i-i 2. it would only require one-half 
 that force to thrust the rock forward, it l)eing absolutely as il made 
 up of .so many more or less vertical piles of dry stouc on dry stone, 
 net at such an inclination as to cause them to uiove forwaid under a 
 .«*tress or pressure of mueli less than half their nwn weight. 
 
 The conclusion therelbrc is that the 4(1,87.') lon^ svater jncssure 
 could and did cause ilic still existing poriinn ol' the cliff /> C to niove 
 forward at /> or alonu /> A', whert' it eiMiie in enntaet with ihe portion 
 A'i^and caused it to fall forward. 
 
 Hut the resistance of the cliff to a motion forward of some •• inches 
 may have been, and probably was. nnieli le» iven than a>-unicd, as 
 it had been raining i-ontinuallv for .'! or 4 days before the accident 
 (showing that no ailoAvanee need be made for I'vaporation ii'oni soil so 
 thoroughly saturatd as it must have been under the ciieumstanoes), 
 and the planes of cleavau'c and other tis>uies in all directions must have 
 been so well lubricated, there i)eing thin hcils or strata oi uneinou< 
 I'lay betwen them, a- to have allowed the rock to move foi wnrd by 
 the mere effect of gravity almost a> does a vessel on its ways set at a 
 much h'ss inclination to the lioriKintal. 
 
 That the movement I'orward wa^ at .1 only some li to 7 inches is 
 still evidenced by the fact that the dislocation in the sliiirway from the 
 'IVrrace level, 182 ft. above the St. Lawrence, up to tlie r,inip;.rt heights, 
 
10 The Quehc.c Land Slih. 
 
 gives just tlijit separation, ami tlie Terrace flooiiug, which hail been 
 scribetl to fit the rocky crags ah)iig tlio rear Hue thereof sliow to tliis 
 day, ;is tliey did the very moment after the avalanche, a separation of a 
 like number of inches northeastward of .1 and decreasing or dying 
 out at about I'jO ft. still eastward therefrom. 
 
 If there still remains any douot as to the cause wliich brought 
 about the result, what other force can it bii a-crihed to ? Tlie only 
 other c.iuse that could be assigned would be :m earth(juake, a ujoment- 
 .ary (juake or shock ol the earth's t-rust at the jjoint in (|Uestion, and 
 this could not have occurred without Vicing noticed by someone at an 
 hour when everyone was up and doing, as was the case wlien tiic 
 accident occurred between 7 and S on the evening of the date recorded; 
 and the very fact (if the still persistent jiortion of the cliff having 
 moved forward by only a flnv inches is proof incontrovertible that it 
 must be due to the cnuse assigned, as any (ither force like that of an 
 earthquake cnuld nevei" Iiave been so instantanedus as to stop short at 
 a mere (5 inch move, while this is fully e.xplained in the case of the 
 cause Mssigued, where, the moment the cliff moved forward, thereby 
 increasing tho capacity of the fissure, the water level at D in)mediately 
 sank and decreased the pressure against the rock in a way not to continue 
 it, and even though the eo-ethcient of rriciion of stmie on stone in motion 
 is but .7 of what it is at rest, or the resistance only .5 (.71 x .7 = .497) 
 of the total weight of cliff. 
 
 The greatest stress the author supposes to have licen exerted at the 
 " centre of pressure '' and upwards, or between it and the centre of 
 gravity, where the loose material filling the fissure E B would allow 
 of being crushc'd into a less bulk, and thus brought about a contact 
 between the pushing rock and that pushed over. 
 
 (leneral Cameron and Major .Mayue of the lloy:ii Military College, 
 Kiiig.ston, who reported to the Federal Government on the subject in 
 1889, or just after the accident, were of opinion that the fallen portion 
 of tlie cliff had given by sliding out at the base • but this view, the 
 author .submits, can hardly be maintained, as in .sueii ca.se the vegct- 
 ablt; mould, grasses ami otlier growths ,it B would have been found at 
 F, whil(', on the contrary, they were found at the e.\tremc outer edge 
 of tho fallen debris, showing that, as testified to by .several wltnes.ses, 
 the cliff aetuilly fell forward from the top. 
 
DISCUSSION. 
 
 Mr. Ciininghain said it was an ixtromoly iotercsting paper ami on bl'iii. ' "'''"^' 
 a very unusual subject. It seemed to him tliat the principal jioiiit is 
 that the remaining rock is in very f^rout danger of tailing, and that 
 some means miglit be devised to prevent this filling in of wnter which 
 appears to have been the initial cause of the upsetting. I'ossibly tho 
 best thing to do would be to drive a tunnel from the face to drain off 
 all these creviissen, so that as the water falls in it will be carried off by 
 the tunnels and drain away, [f it is as Mr. BailLiirge states, and such 
 would appear to be an incontrovertible fact, then the remaining portion 
 of the clitf under the present conditions will also go. 
 
 Mr. Baillairge said yes, this would no doubt be effective in Mi. n.iiiiaiig* 
 removing infiltrated water, which even if insufficient in (juantity to 
 fill one or more of the crevasses between ^-1 and B on section, Plate VII, 
 and act by hydrostatic pressure, or pressure due to head, might, as in 
 the past, act by pressure due to swelling under frost, thus separating 
 the component vortical layers or strata more and more during each .suc- 
 cessive year, until the outer stratum were pushed over, to be succeetied 
 in course of time or followed up by other strata in the rear. 
 
 Mr. Peterson asked what was the part of the cliff that fell out? Mr. iviernon. 
 
 Mr. Baillairgt5 : — Thi.s is shown on plan, Plate IV, between letters mi- ijuiuairge 
 A B G io the left, E FG to the right, (J D E to the rear, and tho 
 front line by the words, " foot of cliff before accident," as also by the 
 words, " fallen -cliff say 300 ft." between B and F, the average length. 
 
 The same is sliown in section, Plate VII, between letters ii Pand /' 
 G, and again in section, Plate VI, leftward of D, where the words 
 occur, " fallen fxirtion of clilf say 30,000 tons." 
 
 Mr. Cuuingham said, was not the idea of tunnelling in from the front Mr. < uning- 
 aud draining all tiiesc crevasses tho most practical one ? 
 
 Mr. Baillairge : — The most practical, the surest and safest plan m,. niu.iaiig^ 
 would be to demoli.><h or cut down tiie cliff, allowing the fallen debris 
 to find their own level at about 1^ iiorizontal to 1 vertical (as such 
 material docs when dumped into embfaiUmont for a railway, etc.), thus 
 hastening what the hand of time is sure to do in the long run. 
 
12 Dis'mssloii on Quebec Land Slide. 
 
 This, liowevor, would destroy soiuj ;?00 ft. of the .southwestern 
 I'lid of the Terrace, which oui" people are loath to part v.itli, and neccs- 
 .situte the shifting of that portion of Ohauiplain street further tovvard.s 
 the St. Lawrence,'thc estimated co.st of dohvj; whieh is not less than 
 $()0, 00(1. 0(1. 
 
 Now to siive the Terraee and avoid the necessity of .shifting the r(j.id- 
 way. the author proposes that a fetainiiii^ wall be built some ;»00 ft 
 in length, 40 ft. liijili, 20 ft. thick at bnttoni aixl 15 ft. at top, batter- 
 ini!; back 5 ft. in the 40 (ir 1 in S. and wi(li layers perpendicular to the 
 batter or dipping towards the eliti', so tiuit any elfort to thru>t the 
 wall forward must be increased l)y the neees-iity to lift the wall ah>ng 
 an inclined plane nl' 1 in 8. tlie ruck foundation invini:;' to be lut or 
 stepped to tiiis slupe I'or the purpose. 
 
 The outiyinjj,' debris whieii now cover tlie roadway to a depth of 
 .-ay 20 ft., and render access to our drainage and water mains an 
 alino.>-t hopeless and very exiiensive task, wotild be lifted and swnug 
 into the jSpiiCe between the clitf and wall, thus clearing and relieviug 
 the roadway and leaving some 10,000 yards of stone to be brought 
 from Cap Rouge or elsewhere and dumped down from the edge of the 
 terrace; to coi\ipletc a slope reai-hing high enough to preveut future 
 slides and accic'onts. 
 
 One or more drainage tunnels ,i> piopo.sed by Mr. Cuningham 
 would further eliminate any danger of additional pressure by water or 
 I rest. 
 
 Ml. cuiiiiij;- Mr. L'uniniiham asked has there been anythinu done to check the 
 probable giving away ol the rest of tht,' rock? 
 
 Mr. Biiilliiii;;.-. Mr. Baillairge: — Nothing as yet. 
 
 .Mr. WiiibmiK. iMr. Walbank asked had the drain been noticed before the accident ? 
 The author replied if h:id not. 
 
 »ir WiiUiaiiU. Mr. Walbank nske(i wliat portion of the rainiiill wrnt into thi.s 
 drain ? 
 
 .Ml. liiiiiinir-i. Mr. Haillairge : — Tiie whole of the rainfall of the 11 A iiours pre- 
 ceding the accident, and whieh was 3'4 inches during tiiat interval ot 
 time. The area draining towards the land slide is 90,000 .«quaie ft., 
 and this into .■{•4 inchc-^ gives 25,500 cubic ft. of water, while tlie rain 
 falling dinct on the area intervening belwecn the ereva.sse and the 
 Citadel and glacis gives another 5,000 cubic ft., togetlier some .'50,000 
 or njorc cubic fl. as stated ; nothing, as already explained, having to be 
 allowed for absorption, since, as evidenced by the data frim tiie Obser- 
 vatory, it had been rainiiig coiitiimously for tiie three or four days 
 
Dlsciissidli. (Ill Qiifhrf LdUil Slidi'. 13 
 
 piveediiii; the land slide, and tliat the soil must have been and certainly 
 was most thoroughly drenched and saturatfd in a'way not to require 
 any allowance for absorption. Nor did >uch wcitlicr re(juire any 
 allowance for evaporation, the air beiiin, like the .><>il, >o thoroughly 
 saturated as to be incapable of I'nrther alisorption, sinee it was so la(k'n 
 as to have to be relieved by preci|iitalion. 
 
 Tlie retaining wall at " It c d <• on plan. ! late I\ , was merely some 
 8 ft. high and o to 4 ft. thick, intended to act, as a screen <m" femh-r to 
 prevent falling dchri> inm reaching the opposite -ide ot Champlain 
 street, and thus causing accidents to lil'e, lind) or properly. 
 
 Mr. llannaibrd asked if they had noticed any sign ol its moving Mijiamiaiord 
 since the accident, or had there bein any (di:inge ? 
 
 Xo increase has been iioticd in the bnadtli or amplitude of tlie Mr, Kailiairgd. 
 crevasse at A. I'late Vil, though i os-ibly the leaning over at />' A' may 
 have been slightly increased since 18S!I by the continued opening of 
 the intervening fissures by frost expansion pressure. 
 
 Mr. McNab would like t > know if, when Mr. IJaillairge ni;i<h' his Mr. MoNab. 
 lirst survey, lu' had i.otieed this drain ? 
 
 Mr. Haillairge replieil : — No, this drain had not been noticed at the Mr. HiiiiUiirj^-. 
 time of survey in 1880, it being, tliou-h only a deep-set surface drain 
 along the loot of IIm rip-rap face of the glacis, conifletely tilled in mid 
 sirown over with long r.mk uias;i'> and shrubs. 
 
 Mr. ('uninuhani asked, afler a rain such as we have had ju>t now y.. (juuiug. 
 (4 days), could you sound the crevasses? ''■""■ 
 
 Mr. Baillairg('' : — Yes, the rain (d'the lust few day- at Quebec would Mr. B»illairge. 
 hardly liave done more than saturate the soil, and not have filled the 
 fissure .1 to a depth capable of preventing its being gone into and 
 explored. 
 
 The author would say in conclii-i"ii regarding the planes ol' cleavage 
 that the inclination of the sniface of the cliff at B and /'on section. 
 I'late VII. shows the direction of these planes, wiiieh his ore..;inal or 
 manuscript sketches indicate as existing all throu'^^b the elilf between 
 A or iVand A' ; but they have l^ceii mistaken by the iimraver I'^r mere 
 etchings, and a false impnv'sion conveyed by etching; the enur^ivim.' at 
 ncaily right angle's to the planes of stratilieation. 
 
 He would also add that lor any one wanting to take in the whole ca.^' 
 at a glance, the note at the head of Plate I is suiHciently satisfactory, 
 
 Mr. I3aillairge said he woidd leave a piece ol' the stone from the Mr. linlilHirt'e. 
 debris of the slide, illustrative as it is ol the highly rhoniboidal figure 
 of the component elements of the clilV. 
 
^■RANSACTiONS CAN'. SOC C. E. 
 VOL, Vi' FLATE iV 
 
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 HOW THE ACCIDENT OCCUlJ 
 
 The drain marked '* choked " on plan hav| 
 
 burst where indicated near guard housG 
 
 opposite the Kings' bastion, the citad; 
 
 drainage water from ditches poured 
 
 Med the ** present inner crevasse"; it;: 
 
 pressure thrusting forward by some| 
 
 the intervening mass of rock betwet 
 
 Q'Ljjtt.Ci& "present mner crevass] 
 
 outer crevasse at ODE agai] 
 A B G D E F G and causing' 
 
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 veen the 
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 gainst the rock 
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 THE QUEBEC LAND SLIDE OF 1889 
 
 BY CHAS. BAILLAIRGE 
 
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LIDE OF 1889 
 
 
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 — — — «■*«■> 
 
 
 N. B. The " housei? 3o indicated 
 along wef^ side of Champlain St 
 were after 1880 purchaoed by the 
 Fed. Govt, demolished and a screen wall 
 built along a b c d e to widen street 
 
 and guard against stones from clifi' rolling '^i^^^"^^^'^^=-^-..^V 
 over roadw^ay and thus causing ^"^""^^/^ 
 
 accidents. ..^ _ 
 
 
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QUEIOEIC CSTADEIL 
 
 N. B. The Drain made to 
 
 take surface water from Citadel ditches 
 
 having been choked for years past the 
 
 water burst and ran from it near the 
 
 guard house into the " present crevasse 
 
 by hydrostatic pressure caused the cliff 
 
 between the present crevasse and that ac C D E 
 
 to move forward some 6 inches at D which 
 
 F - ished forward the rock beyond D and caused it 
 
 to fall over. 
 
LAND 
 
 CHAS. BAILLAII 
 
 aa DD DO 
 
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 OHAiyiRL.AIIM STRKEX 
 
SLIDE OF 1889 
 
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TRANSACTIONS CAN. SOC. C. E. 
 VOL VII. PLATE V. 
 
 JANY 21 1880 
 Eleiration or front view of dangerous cliff 
 along Champlain Street from old land 
 slide of 1841 to Smith's lane or to the 
 tJ. S. S. Go's, office, a distance of say 675 
 ft. Scale 40ft. to one inch English measure 
 
 ^/'- <'^^ ' / 
 
TRANSACTIONS CAN. SOC C. E. 
 VOL VII. PLATE VI. 
 
 • Of=" • 
 
 • OfJ- pL/\ti ' Afip' e:le:\//\tio[^ • 
 
 Level 
 
 /as Ft. above Mean T/'de Level 
 of 5h Lawrence River . 
 
 ^%§OM^D HYOFfOSTA-rtC 
 
 fallen Porf-hn of CI/FF 
 say 36 000 htns . 
 
 Weigrht oF Butf-resses 
 as propos&cf in /880 
 /600 f-o 2IOO h>ns each . 
 
 MEAN 
 
 T/DC 
 
 LBVE. 
 
Kf'n^s 
 BasHon 
 
 LLLJUZE 
 
 Citadel Quebec 
 
 • ^<:a^|Q -^ ^O pK- Po • or\e ' ir\cK' 
 
 STREET 
 
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 ^1 
 
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 C. Baiilairge. 
 
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