_________________________________________ Introduction _______________________________ Historical background _______..______________ Present investigations __________________________ Acknowledgments __________.____________ Landslide types _____________________________ Slump earthflow landslides ______..___________ Debris slides and avalanches ______________ Debris flows and mudflows _____________________ Rockfalls and rockslides ___________________ Landslide processes __________________________ Landslide and slope stability problems of Rio de Janeiro ________________________________ Topographic setting _______________________

Introduction, by Fred O. Jones___________ ____________ Regional physiographic and geologic setting________ Cultural developments. _ ________________________ Acknowledgments.. _ _-_--_-__--_______-_____._ Landslides, by Fred O. Jones and Warren L. Peterson___ Topography on the surficial deposits. ______________ Types of landslides.. ____________________________ Slump-earthflow landslides. __________________ Multiple-alcove landslides. _ __________________ Slip-off slope landslides. _____________________ Mudflows-__---_____-___________---________ Landslides along Franklin D. Roosevelt Lake. _____ Areas of extensive landsliding ____________________ Reed terrace area ___-_-_-_--____---___-____ Culture __ _____-__-___-__-_-_-________ Geology ____-__--_____--_____--________ Geologic history. ____ ___________________ Surface-water and ground-water conditions_ Landslides, ____________________________ Lake fill in the Reed terrace area _________ Cedonia area. ______________________________ Ninemile area. _ ____________________________ Geology. ______________________________ Landslides ___-______-----_-_-__________ Seatons Grove-Koontz ville area --___-________ Seatons landslide (No. 7) ________________ Seatons mudflow (No. 320) _ ___________ Koontzville landslide (No. 5)__-_-_____-_-Nespelem River area. ____-_____-__-_-__-____ Geology. ___._________-____--___-_.____ Glacial history. _-__-_.-_____-__________ Landslides _____________________________ Landslides in the Columbia River basalt. __ ________ Summary of possible causes of landslides. _ _______ _. Economics. ____________________________________ Landslides at Grand Coulee Dam_______ ______ Costs of landslides.-________________________ Statistical studies _________-_-___-__-___---__-__-___ Field observations and methods, by Fred O. Jones. Landslide type groups. _ _____________________ Classification units and measurements of the geologic environment.

No abstract

A geological curiosity in the shape of a displaced mass of rock resulting from ice-pressure during the glacial invasion has been partially uncovered in the Voight quarry, three miles north of Elmira, N. Y., and one-half mile south of Latta Brook ravine. Reference may be had to the Elmira sheet of the United States Geological Survey, but the contour lines represent the topography only in a general way. The quarry is located in the face of a ledge which extends out some 300 feet from the main hill. At its southern end the cutting is only 37 feet deep, but the linear extent is nearly 400 feet. The bottom is about 35 feet above the valley level, making the present approximate height of the point 70 feet. Massive sandstones form the bottom of the quarry, but they rapidly thin out, and the upper third is very largely composed of shale. This formation has received the local name "High Point sandstones."' The strata have a northward dip of about 50 feet per mile, and their position indicates that the axial inclination of the Elmira anticline, to which they belong, is fully as great eastward. Their position was, therefore, an important factor in the amount of pressure required to move the load. The south side of the ledge is in the form of steps or small terraces, which remain as they were in preglacial times, and it is down over this serrated slope that the rock mass was shoved. Its present form is indicated much more clearly by the accompanying sketch than it could be by a detailed description. The base or shoe on which the slide occurred is a hard, blocky sandstone 12 inches thick, and it is chiefly owing to this fact that its character can be recognized. Any attempt to delimit the slide must be largely conjectural, owing to the till covering. There are 50 feet of the basal sandstone in sight, and at one point 7 feet of shale and thin sandstones remain

COOKIITS nrrROOUCTica 4 .BaCt~ ot ~ 1nnaticat.101W aleag t.be vppU' Columbia River 6 General •t.ting 8 Olacial history 9 General effect or Lake RooeeYelt on l.aodal1dea U IJe•cript.ion of landsllcle areas , potential :slide areas, and aate _... along preaent bigba7. 12 s~ 33 REFF.P ~NCF.S .)4 I~"TROTl. C'l'ION As part of the pi'Ogram of tbe U. s. Geological ~) ur1ey 1 landslides are being studied in aereral localities i n the nited States. 'l'heae atudiea are directed toward assembling criteria for recognition o.t lru.dslides 1 clas sii'icat.ion, a xi ca1.alo;;il'l€ of remedial or control metboda that hav been eifttctivc. I n tOt: gorge oi too COlumbia Hiver 1n v~uhington, landslides of large magnitude have been active internii.tter. tly &j nee the valley was first incised. Closure of L:ratxi Coulee Lam, '"'i th the consequent riae of water forming .i'rar.klin l~. Hoosevelt Lake, bas introd ced the factor of a r .:.sing and fluctuating water t.able that accc:1tuatee tr.e incidence of la:•dslidir~g. 'Ihis area was s lect.ed for atudy because of the magnltude o1 the l :il'!dslides and the unknown but signti'ioant in.fluc nce of a nuctuat ing water table. l.:ata resultine from the atuc-' ice •.rt.ll be sl..lllmllrbed in a final report. This report deacy•ibcs brie.Oy the lallClslide conditions aloT>.g the hig hway on the west &hore oi' Fra::klin D. Roosevelt T.ake in i'er~J County, :;ashingt.on 1 be twef. ' " n t he KcttJ.e t•alls bridge a r.J a point opposite the mouth of the Spok&r:e River. Areas which have bee r affected by lancisliJ.es are outli:.cd; area~~ \'lhere landslides may occur in tne fut~e due to the effect of the reservoir are pointed out; a nd those areas which are considered safe .from lartdslide action an delineated. 4 '• •. Prior to the conatl'Ucti on ot• Gra. 'ld. Coulee Dam a nd t he crea tian oi Franklin D. Roosevelt Lake in the Columbia Hi.ver Valley, ~•erry County maintained a law-lwel road alo r~ tbe right bank ot the Columbia River. The position of thi e original road can be examined on tt. C ol~unb ia ili.Yer maps, .,-hi ch vnH•e pu~-lished by the u. s. Geologioal S urY~Y in 19.)0 1 in coopt;rati on vti t h the COI"J'B of lk.gineers, e d tt.led "Plan a r!