Geologichazards in NewMexico -part 2 byWilliam C. Haneberg, New Mexico Bureau of Minesand Mineral Resources, Socono, NM 87801

Abstract We at NMBMMR often receivetelephone callsand letters asking if a specific geologic hazard occurs in a certain area and whethei we have maps available showing the locations of earthquake faults, sinkholes, and so forth. Although at first the notion seemsto be an attractive one, this paper does not include small-scalemaps showing the distribution of geologic hazards in New Mexicb.

Introduction

Economics Although there is no detailed estimate of the total costs asso- ciated with geologic hazards in New Mexico, collateral evidence suggests that they are significant. Brabb (1989) estimated that slope stability problems causedat least $4 million damageto state roads and private property in New Mexico between-1973 and dedared disasterareas in December1984 when a number of homes 1983. The National ResearchCouncil (1991)estimated losses of gp to-$1 million per year from mining-induced subsidence,up to 91 million per year from sinkholes, and between gl million ind $10 million per year from hydrocompactive soils in New Mexico. Robinson and Spieker (1978)estimated lossesfrom floods, earth- quakes, landslides, coastal erosion, expansive soils, and other geologic hazards to be about 94.9 billion per year in the United States. Assuming a s%oavenge rate of inflation, their estimate proj-e,cts$f.3 blllion per year, or about 937 per person per year, in 1991.If flood damage is excluded, the last two figures drop to $6.0 billion per year ind $24 per person p"r yuu.IBured ufon these national figures, annual damage costs in New Mexico-are Purpose estimated to be on the order of tens of millions of dollars. 13

Alsoin thisissue NMGS1992 Field Conference p. 52 Newfusulinid data and multiple episodes of ancestralRocky Mountain deformation in the JoyitaHills p. 53 Upcomingmeetings p. 59 NMGS1993 Field Conference p. 59 Hikingto the top of NewMexiceWheeler Peak p. 60 NMGS1992 spring meeting abstracts p.62 Service/News p. 67 Staff Notes p. 68 Experience in other states suggestsgeologic hazards in New to compile maps for a county atlas series, which will consist of Mexico can be avoided or alleviated through careful land-use 1:500,000thematic maps of interest to county Planners, elected planning and engineering design. In a study of geologic hazards officials, and residents. Map themes will include generalized ge- in California, Alfors et al. (1973) concluded that up to 90Voof ology, mineral resources,geologically young faults and volcanic Iandslide damage costs could be eliminated by a combination of deposits, 100-yearfloodplains, depth to water, water chemistry, geologic investigation, engineering design, and enforcement of ground-water pollution potential, slope instability potential, col- zoning laws. Subsequentresearch has shown that this three-tiered Iapsible and./orexpansive soil potential, and other topics. strategy has reduced the costs of landslide damage associated with new construction in California by 927" to 97Vo(National Geologic hazards and geologic events ResearchCouncil, 1985).Bemknopf et al. (1988)conducted a study The distinction between a geologic hazard and a geologicevent to assessthe potential effectivenessof different planning strate- (e.g., Rahn, 1986)is an important one. A geologicevent is the Bies on landslide damage in the Cincinnati, Ohio area. They con- occurrence of any geologic process, perhaps a landslide or an cluded that if grading provisions specifiedin Chapter 70 of the earthquake. A geologic hazard, on the other hand, is a geologic Uniform Building Code were enforced without regard to site- event which has a significant impact upon humans or their works. specificdetails, the benefit:costratio would be 0.98:1.However, In many respects this distinction is analogous to the adage of a if Chapter 70 provisions were enforcedonly in areaswith steep tree falling in a forest with no one to hear the sound. Thus, a slopes,the benefit:costratio would increaseto 1..82:1.Finally, if large landslide in a remote area would be classified as an event, both slope and bedrock type were taken into account, the bene- whereas the same landslide in a heavily developed mountain fit:cost ratio would rise even further, to 2.27:'1..Simply put, en- resort would be classified as a hazard. It is also useful to define forcement of only the most basic grading requirements would potential hazards and potential events as those which geologic save more than twice as much money as it would cost. evidence suggestsmay have occurred in the past, and which may occur in the future, but for which there is little or no evidence of Sourcesof information recent activity. Examplesof potential hazards or potential events The primary sourceof geologic information about New Mexico might include dormant volcanoes or landslide comPlexes.This is NMBMMR, which is also the Office of State Geologist and the distinction has practical significancefor statessuch as New Mex- state agency responsible by law for original investigations of ge- ico, in which limited resourcesmust be used largely to address ology and mineral resourcesin New Mexico. NMBMMR main- specific problems rather than to compile state-wide inventories tains a small environmental and engineering geology staff, which covering vast, sparselypopulated areas. is responsiblefor 1) determining potential environmental impacts caused by intensive development of mineral, water, and land resources;2) evaluatingthe hazard potential of natural geologic processessuch as landslides, debris flows, earthquakes,and ground subsidence;3) siting waste managementfacilities; and 4) devel- oping a comprehensivedatabase, including reports and maps, on these subjects.Lists of publicationsand open-filereports, as New AAexfic@ well as the quarterly New Mexico Geology,are available from the NMBMMR publications office. GEOLOGY Other sourcesof engineeringgeologic and geotechnicalengi- neering information include the New Mexico State Highway De- o Scienceand Service partment GeotechnicalSection, the New Mexico Water Resources rssN 0196-944X ResearchInstitute, the U.S. GeologicalSurvey, the U.S. Soil Con- Volume 14, No. 3, August 1992 servation Service, the State Engineer Office, and geology de- partments and geologicalengineering programs as the University Editor: Carol A. Hiellming of New Mexico, New Mexico StateUniversitv and the New Mex- Publishedquarterly by ico Institute of Mining and Technology (Neiv Mexico Tech). Ad- New Mexico Bureau of Mines and Mineral Rewurces ditional sourcesare included in fohnpeer (1986).The Geology a division of New Mexico lnstitute of Section of the New Mexico State Highway Department has pro- Minint & Technology duced a seriesof geologicand aggregatesource atlases of con- BOARD OF REGENTS siderableinterest to those involved in construction.Guidebooks Ex-Officio Bruce King, Gwernor of Nru Merico compiled for the annual fall field conferencesand other special Alan Morgan, Superintendent ol Public lnstruction publications of the New Mexico Geological Society consti[ute a Appointed valuable source of Lt. Gen. Leo Marquez, Pres.,1989 795, Albu4uerque basic geologic information, as well. Sources Charles Zimmerly, Src.lTreas., 7991 1997, Socorro formaps, aerial photographs, satellite imagery, thermal imagery, Diane D. Denish, 1992-1997, Albuquerque and radar imagery covering the stateare listed in Rex (1991). J. Michael Kelly, 1992-197, Roswll Steve Tones, 1991 1997, Albu4uerque Generalissues related to geologichazards and land use plan- New Mexico lnstitute of Minin8 & Technology ning are discussedat an introductory level by Robinsonand Spieker President. . Laurence H. Lattman New Mexico Bureau of Mines & Mineral Resources (1978)and Hays (1981),and at a more advancedlevel by eooke Director ifld State Ceologist .. . Charles E. Chapin and Doornkamp (1990).Hawley and Love (1981)presented a gen- Subriptions: l$ued quarterl, February Mat Au8ust, eralized summary of geologyas related to environmental concerns November; subscription price $6.00/calendar year. in New Mexico, and Hawley and Longmire (7997)discussed ge- Editorial Mttq: Articles submitted for publication should be in the editor's hands a minimum of five ologic considerationsbearing on hazardous-wastesite selectiron (5) months before date of publication (February and characterizationin New Mexico. The engineering and en- May, August, or November) and should be no longa than 20 typewritten, double-spaced pages. All vironmental geologyof the Albuquerqueareals summlarizedby scientific papers will be reviewed by at least two Lambert et al. (1982),Clary et aI. (l9M), and Hawley and Love people in the appropriate fietd of study. Address (1991,p.734-744). (1983) inquiri6 to Carol A. Hielming, Editor of Nru Metico Johnpeerand Hamil provided a similar Geology, New Mexico Bureau of Mines & Mineral synopsis of the Socorroarea. Johnpeeret al. (1987)and Barrie Resources, Scoro, NM 87801-4796. (1987)summarized the engineeringgeology of the northern Es- Published as public domin, therefore reproducible without tanciabasin with regard to siting of a proposedsuperconducting wrmission. Source credit reouested. 1,6N supercollider. The book New Mexicoin Maps (Williains, 1986)con- Circulation: P/irtel; University of New Mexico Printing Seilices tains a collection of thematic maps covering both the geography and geology of New Metco. NMBMMR is currentlybeglnning

August 1992 Nao MexicoGeology [Sections on earthquakes and land subsidenceappeared in part Brabb, 1987)show evidence of past slope instability throughout l, New Mexico Geology,v. 14, no. 2, pp.34-41.1 much of New Mexico. In many cases,the evidence was limited to nearly vertical escarpmentssubject to rockfalls and topples. In other cases,evidence of large landslide and debris flow deposits Expansivesoils was identified. Although Brabb (1989)rated the landslide hazard Expansivesoils (Fig. 8) of the order Vertisol present foundation in New Mexico as "moderate" and the landslide inventory cov- design problems in urbanized areassuch as Albuquerque and Las erage as "high," landslide susceptibility coverageis described as Cruces (Hacker, 1977;Bullochand Neher, 1980).Gustavson (1991) noneistent and general landslide knowledge is rated as "poor." described the occurrence, pedogenesis,and age of buried verti- Brabb et al. (1989)conducted a series of computerized statistical sols in the Fort Hancock Formation, Hudspeth County, Texas.In analysesof landslide deposits and slope angles derived from dig- an earlier paper (Gustavson, 1975)he reviewed identification mi- ital elevation models and found that the occurrenceof landslide crotopographic features (gilgai) and engineering problems asso- deposits could be correlated with slope angle. Shallow landslide ciated with vertisols along the Texascoastal plain. Much of this deposits were reported most likely to occur on slopes of about work can be applied to New Mexico, where the most severe 22", whereas deep landslide deposits were rePorted most likely problems are causedby smectitic soils such as those of the Armijo to occur on slopes of about 10'. Brabb et al. (1989)also reported Series. Armijo soils form in alluvial loams and clays deposited that earlier, nationwide maps of landslide susceptibility (Krohn along the Rio Grande floodplain and the clays, in particular, have and Slosson,1976; Radbruch-Hall et al., 1981)seriously under- high shrink-swell indices. estimated the occurrenceof landslides in New Mexico. In other cases, smectitic shale bedrock has caused highway Evidence of past slope instability is one of the key elements in construction problems, for example in CretaceousMorrison For- the delineation of potentially hazardousareas (Nilsen, 1986;Han- mation shales excavatedalong I-40 between Santa Rosa and Tu- sen, 1984);therefore, even if slope instability is not currently a cumcari (Kelley and Kelley, 1972).This section of highway was significant hazard, the possibility should be incorporated into graded, rolled, and sealedwith an asphalt membrane to prevent long-term planning decisions in areas of prior instability. Reac- moisture infiltration. tivation of large landslide complexes in Utah during the 1980s, Geotechnicalexploration procedures in areaswhere expansive soils may be a problem should include a review of county soil surveys and analysis of clay mineralogy in order to estimate the general potential for shrink-swell problems. Once areasof ex- pansive soils have been identified, laboratory testing of shrink- swell potential can yield quantitative information useful for foun- dation design. Remedialmeasures include removal of shallow type locality near Toreva, Arizona) in northwestern New Mexico problem soils, pre-compactionor pre-wetting, deep foundations, and northern Arizona. The costsassociated with the reactivation and elimination of moisture sources(Das, 1984, pp. 460-474). of a largelandslide complex can be sobering:Fleming et al. (1988), for example, estimated total costs of nearly $2 million to repair damage and prepare for future movement when the Manti land- slide in Utah, some 5.5 km from the nearestdwelling, was re- Slope instability activatedin1974. At this point, the types and magnitudes of weather and/or Evidencefor past slope instability climate change that would be necessaryto reactivate large land- Slope instability is not currently a significant geologic hazard slides in New Mexico cannot be predicted. However, it is clear in most parts of New Mexico although landslides,debris flows, that above-averageamounts of rainfall can reactivate dormant and rockfalls are a persistent problem along some mountain high- landslide complexes. For example, a Toreva block slide occurred ways. In places where slope stability is a problem, however, the along an outlier of the High Plains escarpment, known as Twin cost is high both in termsof dollarsand of human lives. Regional Mesa, in De BacaCounty during early September1991 (Fig. 9). landslide inventories based upon aerial photograph and topo- The failure mass consisted of Chinle Formation siltstone capped graphic map interpretation (Cardinali et al., 1990; Guzetti and by a l-m-thick calcrete, and highly weathered blocks along the base of the mesa suggest that Toreva block sliding has been a significant agent of slope retreat in the past. The surface area of the reactivatedslide was about 200x 200m, with a 2- to 3-m-high

fied the theoretical relationship between storm intensity, storm duration, pre-storm soil-moisturecontent, and the hydrologic responseof landslidesto rainfall. The time-dependencyof pre- stoim soil-moisture content, however, makesit difficult to predict the responseof a given landslide (or potential landslide) to a given storm. Human activity, especiallyroad building in mountainous areas/ can createor exacerbateslope-stability problems. Bennett (1974) describedwidespread slope-stabilityproblems in nearly saturated landslide debris, derived from Pleistoceneoutwash depositedover CretaceousMancos Shale along 30 km of U!64 between Tierra FIGURE 8-"Popcorn" texture characteristic of vertisols subjected to re- Amarilla and Tres Piedras in eastern Rio Arriba County. These petitive wetting and drying In addition to qualitative criteria, standard failures are concentratedin cut and fill slopesalong the right of soil mechanics procedures to quantitatively estimate the shrink-swell po- preliminary geologicstudies, tential of clay-rich soils are described in soils and foundation engineering way, and Bennett notes that only textbooks (e.g., Das, 1984)

Nau Mexico Geology August 7992 FIGURE l1-Remains of a debris flow along the Rio Grande that occurred during a storm in late July 1991. The unsorted, bouldery, lower portion of the deposit, which is characteristic of debris flows, could be traced across the river after the flow, suggesting that the Rio Grande was tem- porarily dammed Even though the dam was quickly breached, the re- sulting constriction continued to limit flow when this photo was taken in Seplember 1991. Other debris flows and flood flows clogged box cul- verts and blocked NM-68 during the same storm.

FIGURE 12-Aftermath of the Cordova debris flow of June 1990. Ap- proximately 10,000 cubic meters of sand, gravel, and cobble stream-terraie deposits were transformed into a flowing mass of debris when an over- irrigated pasture failed as a landslide. The barren head scarp of the original failure is visible in the middle ground. Coarse granular soils, such as those along stream terraces near Cordova, have high mobility indices and are likely to mobilize into fast-moving flows if the soils are saturated and shear

August 1992 Nm MexicoCeology with no provisions for slope-stability analysis, were conducted Chavez, Colfax, Eddy, Grant, Lea, Lincoln, San fuan, Sierra, Quay, prior to construction. Another reactivation of an obvious land- and Union. slide complex occurred in Cretaceousshales and limestones cap- Low radon availability-Less than 2.3 ppm uranium on aerial ped by Quaternary basalts during construction of l-25 betrareen radiometric maps and, in general, low-permeability soils. Coun- Sprlnger and Raton in Colfax County (Lovelace, 1976).A large ties falling into this category are Curry, De Baca, Guadalupe, landslide, apparent$ reactivated by seepagefrom abandoned mine Harding, Mora, Otero, Roosevelt,San Miguel, Torrance,and Va- workings, affected a number of homes near the Taos ski valley lencia. in 1979; remedial measures included installation of horizontal drains and diversion of surface water, which increased the pre- It is important to emphasize that these ratings are preliminary slide factor of safetyof 0.92 to 1.28(Bennett, 1979). estimatesof radon availability averagedover entire counties, and An abundance of large boulders suggests that rockfalls have not the actual radon concentrated within a given building at a been a common occurrencealong the Rio Grande gorge between given time. Therefore, it is possible for homes in high-availability Rinconadaand Pilar. To help mitigate the hazard, the New Mexico counties to have low indoor radon values, and for homes in low- StateHighway and Transportation Department has installed rock- availability counties to have high indoor radon values. Site-spe- moisture bedrock fall protection nets in Quatemary landslide debris along NM-58 cific details such as soil type and content, soil or near Embudo. Severalmiles farther north, five people were killed fracture systems, foundation type, ventilation, and time of year and fourteen injured when a commercialbus struck a basaltboul- can all produce widely scatteredindoor radon readings in nearby der along NM-68 in September 1988,and a 270,000kg boulder buildings. (Fig. 10)left a 5x5x14 m craterin the highway after aluly 1991 Brookins (L988,l99l) measured radon concentrationsthrough- rockslide. Dynamic analysis suggeststhat the 1991boulder was out the Albuquerque area. He found that nearly 30% of homes traveling at a velocity of about 2l mJs and struck the highway had indoor radon levels above the EPA action level of 4 pCr/\, with an estimated kinetic energy of 108N.m (Bauerand Haneberg, and that soil radon levels were 2 to 4 times the national average 1992), which is several hundred times the capacity of commei- of approximately 100 pCi/I. The higher soil radon values were cially availablerockfall protection nets. The samestorm produced measured during the summer, whereasthe lower soil radon levels at least 11 debris flows (Fig. 11) and an unknown number of were measured during the winter. Brookins noted correlations smaller rockfalls, which trapped 20 automobiles along the high- between 1) soil radon and indoor radon concentration, 2) soils way and temporarily dammed the Rio Grande. NM-58 was closed developed over bedrock and indoor radon concenhation, and 3) indoor radon concentra- for L9 hours and cleanup costs were approximately $75,000(P.W. proximity to the Sandia Mountains and Bauer, personal communication 1992i.^ tion. He also found a weaker correlation between summer soil Potentially hazardous slope failures can also occur in areaswith radon concentrations and soil infiltration rates, and no correla- and soil texture or no evidence of past instability. In June 1990, a debris flow was tions between soil radon concentrations mois- mobilized from a small landslide in Holocene stream terrace de- ture content. posits east of Espanola near the town of Cordova in Rio Arriba County (Fig. 12; alsosee Haneberg and Tripp, L990,l99L).Neither the Guzetti and Brabb (1987)regional map nor visits to the site suggested evidence of past slope instability in the area. Failure was apparently caused by long-term accumulation of perched Volcanism water along one of severalfine-grained, buried soil horizons within Geologically young volcanic rocks, the product of at least 700 the coarse-grainedterrace deposits, and Iaboratory test results eruptions over the past 5 Ma (Limburg, 1.990),cover large areas show that the debris mobilization could have been predicted on of New Mexico. Using these figures, the average state-wide re- the basis of soil properties. Gradient reversalsand smatl leaks in cunence interval for volcanic eruptions is about 7,000years. Al- an unlined irrigation ditch above the failure suggest that pro- though there is an apparent increasein the number of eruptions gressive fai]ure had been occurring for some time, althoughthe through time during the past 5 Ma, it is almost certainly caused pre-dawn debris flow was rapid. The volume of debris wis not by the difficulty in discovering and dating the remnants of older great, on the order of 10,000m3, and the only damagewas burial eruptions. A map by Callender et al. (1983)shows the distribution of an unimproved dirt road, diversion of a small stream, and loss and agesof known Quatemary and upper Pliocenevolcanic rocks of pasture land. However, the existenceof untold miles of com- (less than 5 Ma), volcanic centers, and geothermal waters. Most munity irrigation ditches, many dating back severalcenturies, in of the young activity has been in the form of effusive basaltic steep terrain makes future irrigation-induced failures in northern eruptions, presenting little danger beyond the loss of property. New Mexico a potential hazard. The presenceof the rhyolitic |emez volcanic center in north-cen- tral New Mexico, as well as numerous maars and tuff rings throughout the state, suggests that the possibility of a violent eruption cannot be ignored completely. In addition to the poten- tial hazards posed by a blast, heavy snowpacks in mountainous Radon areas such as the Jemez could give rise to catastrophic debris The widespread occurrence of uraniferous sedimentary and flows and floods in the event of a winter or spring eruption. A igneous rocks makes inhalation of radon gas a potential hazard 19-km-deep mid-crustal magma body of unknown composition in many parts of the state. As part of a preliminary state-wide (Sanford 1983) between Socorro and Bernardo may also pose a assessment,Mclemore and Hawley (1988)used aerial radiometric Iong-term volcanic hazard, although there is no evidence to sug- surveys to compile radon availability ratings for the 33 counties gest that eruptions will occur in the near future. in New Mexico. Radon availability ratings in the Mclemore and Volcanologists L Yokoyama, R.I. Tilling, and R. Scarpa (cited Hawley (1988)study of New Mexico were defined as follows: in Scott, 1989)have proposed a numerical rating schemefor the identification of high-risk volcanoes,based upon a combination High radon availability--Creater than 2.7 ppm uranium on aerial of magma type, recent eruptive activity, and the number of people radiometric maps and, in general, well-drained and permeable at risk. High-risk volcanoesare defined as those receiving scores soils. Counties falling into this category are Dofra Ana, Hidalgo, of 1.0or above. Using this rating system, the volcanic com- Los Alamos, Luna, McKinley, Jemez Rio Arriba, Sandoval, Santa Fe, plex would receivea scoreof 2, whereas the Socorromagma body Socorro,and Taos. would receivea scoreof 3 to 5, depending on magma composition Moderate radon availability-2.3 to 2.7 ppr,:.uranium on aerial and the number of people affected. Mt. St. Helens and Kilauea, radiometric maps and, in general, moderately permeable soils. the two most recently active volcanoesin the United States,rate Counties falling into this category are Bernallilo, Catron, Cibola,

Neu Mexico Geology August 1992 scores of L5 and 13, respectively. Other high-risk volcanoes in Referencesfor parts 1 and 2 the United States, each rating a score of 10, are Lassen Peak, Mauna Loa, and Mono-Inyo Craters. This rating system is sus- Alfors, J. T., Bumett, J. L., and Gay, T. E., Jr., 7973,The nature, magnitude, and ceptible to failure if information on historical activity is scanty or costsof geologichazards in Califomia and recommendatiosnfor their mitigation: nonexistent, as shown by the catastrophic1985 eruption of Nev- Califomia Dvision of Mines and Geology, Bulletin 198, 112 pp. Algemissen, S. T., Perkins, D. M., Thenhaus, P C., Hanson, S. L., and Bender, ado del Ruiz in Colombia, which was not on the original list of B. L., 7991,Probabilistic earthquake acceleration and velocity maps for the United high-risk volcanoes prepared by Yokoyama and his colleagues. Statesand Puerto Rico: U.S. GeologicalSurvey, MiscellaneousField StudiesMap Compared to other areasof the world, however, volcanic hazards MF2720. 2 sheets.scale 1:7,500,000. in New Mexico appear to be minor and of consequenceto only Anderson, R. Y., 1981, Deep-seatedsalt dissolution in the Delaware Basin, Texas and New Mexico; inWells, S. G., and lambert, W. (eds.), Environmental geology the most sensitive of facilities, for example national laboratories and hydrology in New Mexico:New MexicoGeological Society, Special Publication and nuclear-waste facilities. no. 10, pp. 133-145. Bachman, G- O., 1974, Geologic processesand Cenozoic history related to salt dissolution in southeasternNew Mexico:U.S. GeologicalSuwey, Open-file Report Summary 74-1.94,87pp. Bachman, G. O., 19U, Regional geology of Ochoan evaporites, northem part of Actual and potential geologic hazards in New Mexico cover a Delaware Basin: New Mexico Bureau of Mines and Mineral Resources,Circular broad spectrum from earthquakes to collapsible soils to land- l84,22 pp. slides. No estimates of economic impact are available, but hy- Banie, D., 1987,Engineering geology of the northem Estanoa Valley, north-central New Mexico: Unpublished MS thesis, Socono, New Mexico Institute of Mining drocompactive (collapsible)soils are probably the most significant and Technology, 110 pp. actual geologic hazard in the state. However, the most significant Bauer, P W., and Haneberg, W.C., 1992,Geologic setting for rapid mass-wasting potential hazard is probably a large earthquake on the order of in the Rio Grande gorge area, Taos County, New Mexjco (abs.): New Mexico magnitude M : 7, with an estimated recurrenceinterval on the Geology,v. 14, no. 3, p.63. Baumgardner, R. W., Jr., and Akhter, M. 5., 7991, Geomorphology and surface- order of 103years. Recent experiences in Utah have shown that water hydrology of part of the Hueco Basin, west Texas:West TexasCeological landslideand debris-flowhazards, along with damagecosts, can Society,Bulletin, v. N, pp. 527. also be expected to increasesignificantly during wet periods. A Beehner,T.5., 1990,Burial of fault scarpsalong the Organ Mountains fault, south- wealth of unanswered questions concerning the distribution, central New Mexico: Bulletin of the Association of Engineering Geologists, v. mechanisms, and XXVII, pp. 1-9. mechanicsof hazards makesNew Mexico fruit- Ben,l. W., Ramelli,A. R., dePolo,C. M., Maurer,D. K., and Prudic, D. E.,1989, ful ground for basic and applied researchon potentially hazard- Extensionalcracking along an active normal fault: a casefor creePon a Basin and ous geologicprocesses. Range fault? (abs.): SeismologicalResearch Letters, v. 60, p. 30. Considering the wealth of practical experience with geologic Bell, J. W. and Hoffard, I. L., 7990,Late Quaternary tectonic setting for a possible fault creep event in the Pine Nut Mountains area, western Nevada (abs.): Geo- hazards in New Mexico, it was disappointing to find that many logical Society of America, Cordilleran Section, Abshacts with Protrams, v. 22, case histories have never been adequately described in the sci- o.7. entific and engineering literature. The communication of tech- B€nnett, W. T., 1974,Landslides on "BrazosPass": New Mexico GeologicalSociery, nical information is a professionalresponsibility, no lessimportant Guidebook to 25th Field Conference,pp. 359J63. Bennett, W. , 1.979,Interimgeotechnical report, Twining landslide: New Mexico State than the classifying of rocks or the making of maps. Although Highway Department, intra-departmental conespondence from W. Bennett to internal memoranda and conversationsmay be adequatefor day- J.D. Winton, September14, 7979,8 pp. to-day project work, they can be practically uselessto those who Bemknopf, R. L., Campbell, R. H., Brookshire, D. S., and Shapiro, C. D., 1988,A come afterwards. Even the abstractsand proceedingsvolumes of probabilistic approach to landslide hazard mapping in Cincinnati, Ohio, with applications for econonic evaluation: Bulletin of the Association of Engineering so-callednational meetings may be effectively impossible, at least Geologists,v.ilV pp. 39-5e. for those outside a small circleof attendees.to find and cite. Berzins, G., 1985,Assessment of gravity anomaliesover mine tunnels: Unpublished There is, in theory, no reasonwhy economiclosses associated MS researchpapet New Mexico Institute of Mining and Technology,Geophysics with geologic hazards could not be virtually eliminated in New Program, 72 pp. Brabb, E. E., 1989,Landslides: extent and economicsignificance in the United States; Mexico. Hazards brought on by human activity-for example, in Brabb, E. E., and Harrod, B. L. (eds.), Landslides: extent and economic sig- landslide reactivation during construction, hydrocompaction, and nificance: 28th Intemational Geological Congress Symposium on Landslides, subsidence caused by fluid withdrawal--can be predicted using Washington, D.C., July 17,1.989,Proceedings, pp. 25-50. well-known methods of hazard zonation and geotechnical site Brabb, E. E., Guzzefti, F., Mark, R., and Simpson, R. W., Jr., 1989,The extent of landsliding in northern New Mexico and similar semi-arid and arid regions; in investigations.Other hazards,such as earthquakesand volcanic Sadler. P. M., and Morton, D. M. (eds.), Landslidesin a semi-arid environment: eruptions, can only be anticipated and prepared for, making re- Publications of the Inland GeologicalSociety, v. 2, pp.1.63-173. duction of damage somewhat more difficult. The consequences Brookins, D. G., 1988,The indoor radon problem: shrdiesin the Albuquerque, New of unprecedentedactivities such as over-irrigation,intensive log- Mexico area: Environmental Geology and Water Science,v. 12, PP.24 42. Brookins, D- G., 7991,,Correlation of soil radon and uranium with indoor radon in ging, or construction in previously undeveloped areascannot be the Albuquerque, New Mexico area: Environmental Geology and Water Science, anticipated from past experiencealone. Therefore, field and lab- v. 17, pp.2W-217. oratory investigations by qualified engineering geologistsor geo- Bulloch, H. E., Jr., and Neher, R. E., 1980,Soil suruey of Dofla Ana County area, technical engineers should becomea routine part of the planning New Mexico: United StatesDepartment of Agriculture, Soil ConseruationSeruice, + and development processin New 7n pp. maps. Mexico. Site investigations typ- Callender, J. F., Seager,W. R., and Swanberg,C. A.,1983, Late Tertiary and Qua- ically add only IVo or2Vo to total project costs, and incorporation ternary tectonicsand volcanism: GeothermalResources of New Mexico, Scientific of even the most elementary geologic knowledge into planning Map Series,New Mexico StateUniversity EnergyInstitute, 1 sheet,scale 1:500,000. and zoning decisions can result in significant long-term savings. Cardinali, M., Guzetti, F., and Brabb, E. E., 1990,Map showing landslide deposits in New Mexico: U.S. GeologicalSurvey, Open-file Report 90-293, 4 sheets,scale In short, it costs less to identify geologic hazards and take cor- 1:500,000. rective action than it does to repair the damage later. However, Clary, J. H., Korecki, N. T., and Mondragon, R. R., 1984,Geology of Albuquerque, many New Mexicans have yet to grasp the fact that geologic New Mexico, United Statesof America: Bulletin of the Associationof Engineering hazard assessmentand avoidance can be an integral part of Geologists, v. XXI, pp. 727-155. sus- Clemence,S. P, and Finban, A. O., 1981,Design considerationsfor collapsingsoils: tained economicgrowth, and the role of agencies suchas NMBMMR Joumal o( Soil Mechanics and Foundation Engineering, GT3, pp. 305-317. will probably be one of reaction rather than prevention well into Contaldo, G. J., and Mueller, J. E., 1988, Earth fissures in the Deming area: New the foreseeablefuture. Mexico Geologic Society,Guidebook to 39th Field Conference,pp. 3-5. AcrNowlrpcMENTS-A preliminary version of this review was Contaldo, G. J., and Mueller, J. E.,1991,a,Earth fissuresand land subsidenceof the Mimbres Basin, southwestern New Meico, U.S.A.; in Johnson, A. I. (ed.), Land presentedat the 4!st Annual Highway GeologySymposium, Al- subsidence(Proceedings, Fourth Intemational Symposium on Land Subsidence, buquerque, August 15-17, 1990.Earl Brabb, JamieGardner, fohn Houston, Texas,May 12-18, 1997):Intemational Associationof Hydrological Sci- Hawley, Gary fohnpeer, Ellen Limburg, David Love, and Allan ences, Publiation no. 200, pp. 301-310. Sanford provided some of the information incorpoiated herein. Contaldo, G. J., and Mueller, J.8., 1997b,Earth fissures of the Mimbres Basin, southwestern New Mexico: New Mexico Geology, v. 13, pp. 69-74. |ohn Hawley, David Love, Gary Johnpeer, and Warren Bennett Cooke,R. U., and Doornkamp,I. C.,1990,Geomorphology in environmentalman- reviewed drafts of this paper. agement: Oxford, Clarendon Press,2nd edition, 410 pp.

August 1992 Nao MexicoGeology Curtis, W. D., and Toland, C. C., 79U, Foundations on moisture sensitive soils: HiU, C. A., 1987, Geology of Carlsbad Cavem and other caves in the Guadalupe Dames & Moore Engineering, Bulletin 25, pp.3-12. Mountains, New Mexico and Texas: New Mexico Bureau of Mines and Mineral Das, B. M., 1984, Principles of foundation engineering: Boston, PWS Publishers, Resources,Bulletin 117, 150pp. 5es pp. Holze\ T. L., editor, 1984a,Man-induced land subsidence:Geological Society of Davies, P. 8.,1989, Assessingdeep-seated dissolution-subsidence hazards at radi- America, Reviews in Engineering Geology VI,221, pp. oactive-wasterepository sites in bedded salg in Johnson,A. M., Burnham, C. W., Holze+ T. L., 19Ub, Ground failure induced by ground-water withdrawal from Allen, C. R., and Muehlbergea W. (eds.), Richard H. Jahns Memorial Volume: unconsolidated sedimenf inHolze\ T. L. (ed.), Man-induced land subsidence: Engineer.ingGeology, v. 27, pp. 467-84. Geological Society of America, Reviews in Engineering Geology VI, pp. 67-105. dePolo, C. M., and Slemnons, D. 8., 1990,Estimation of earthquakesize for seismic House,L. S., and Cash,D. J.,1988,Areviewof historicandinstrumentalearthquake haards; in Krinitzsky, E. L., and Slemmons, D. B. (eds.), Neotectonicsin earth- activity and studies of seisnic hzards near Los Alamos, New Mexico:Los Alamos quake evaluation:Geological Society of America, Reviewsin Engineering Geology National Laboratory, Rept. LA-11323-MS, 41 pp. VIII, pp. 1-28. fohnpeer, G. D., 198f, Geotechrucalinvestigations and data sourcesin New Mexico: El-Hussain, I., and Carpenteg P. J.,79X, Reseruoir-inducedseismicity near Heron New Mexico Geology, v. 8, no. 1, pp.14-79. and El Vado Reservoirs, northem New Mexico: Bulletin of the Association of Johnpeea G. D., Bobrow, D., Robinson{ook, S., and Banie,D.,7987, Preliminary Engineering Geologists,v. XXV[, pp. 51-59. study for siting the superconducting super collider in New Mexico: New Mexico Flening, R. W., and Schuster,R. L., 1985,Implications of the current wet cycle to Bureau of Mines and Mineral Resources,Open-file Report 257, 65 pp. landslides in Utah; ln Bowles, D. S. (ed.), Delineation of landslide, flash flood, Johnpeer, G. D., and Hamil, B. M., 7983,Engineering geology of the Socono area, and debris flow hazardsin Utah: Utah Water Researchl-abomtory, General Series, New Mexico: New Mexico GeologicalSociety, Guidebook to 34th Field Conference, Report UWRUG-85/03, pp. 19-28. pp. 339-34a. Fleming, R. W., fohnson, R. 8., and Schuster,R. L., 1988,The reactivation of the Johnpeer, G. D., Love, D. W., Hawlet J. W., Bobrow, D., Hemingway, M., and Manti landslide, Utah: U.S. GeologicalSuruey, Professional Paper 1311-A, 22 pp. Reimers, R. F., 1985a,El Llano and vicinity geotechnicalstudy-interim rePort, Foley,L. L., Lalorge, R. C., and Piety, L. A., 1988,S€ismotectonic study for Elephant prelininary results of ground subsidenceinvestigation: New Mexico Bureau of Butte and Caballo Darns, Rio Grande Project, New Mexico: U.5. Bureau of Rec- Mines and Mineral Resources,Open-file Report 226, 398 pp. lamation, S€ismotectonicReport 88-9, Seismotectonicsand GeophysicsSection, fohnpeer, G. D., Love, D. W, Hawley, J. W., Bobrow, D., !emi1g_way, M., and Geology Branch, Division of GeotechnicalEngineering and Geology, Denver Of- Reimers,R. F., 1985b,El Llano and vicinity geotechnicalstudy-final report: New fice,67 pp. Mexico Bureau of Mines and Mineral Resources,Open-file Report 226, 578 pp. Friesen, R. L., and Haneberg, W. C., 7992,Digital documentation of deformation Johnpeer,G. D., Love, D. W, and Hemingway, M., 1985,Assessment of earthquake and ground-water levels near an earth fissure in the Mimbres Basin,New Mexico hazards in New Mexico: Earthquake Engineering ResearchInstitute, Oakland, (abs.): New Mexico Geology, v. 14. no. 3, p. 63. Califomia, Proceedingsof the Third U.S. National Conference on Earthquake Gardner,J. N., and House, L., with contributions by 11 others, 1987,Seismic hazards Engineering, August 24-28, 1986,Charleston, South Carolina, v. I, PP. 233JM. investigations at Los Alamos National Laboratory 1984to 1985:Los Alamos Na- Keaton, J. R., and Shlemon, R. 1., 1991,The Fort Hancock earth fissure systen, tional Laboratory, Rept. LA-11072-M5,76 pp. + maps. Hudspeth County, Texas:uncertainties and imptcations; in Johnson, A. I. (ed.), Gile, L. H., 1,987,Late Holocene displacementalong the Organ Mountains fault in Land subsidence(Proceedings, Fourth Intemational Symposium on Land Sub- southem New Meico: New Mexico Bureau of Mines and Mineral Resources, sidence, Houston, Texas,May 12-18,1991):International Association of Hydro- Chcular 196, 43 pp. logical Sciences,Publication no. 200, PP. 2U)n. Gustavson,T. C.,1975, Microrelief (gilgai) structureson expansiveclays of the Texas Kelley, V. C.,7972, Geology of the SantaRosa area: New Mexico GeologicalSociety, coastal plain-their recognition md significance h engineering construction: Univ. Guidebook to 23rd Field Conference,pp.278-220. of Texas(Austin), Bureau of EconomicGeology, GeologicalCircular 75-5, 18 pp. Kelley,V. C., andKelley,R.W.,1972, Roadlogof Tucumcari,CanadianEscarpment, Gustavson,T. C.,7997, Arid basin depositionalsystems and paleosols:Fort Hancock and SantaRosa country: New Mexico GeologicalSociery Guidebook to 23rd Field and Camp RiceFormations (PliocenePleistocene),Hueco Bolson,west Texasand Conference,pp. 45-55. adiacent Mexico: Univ. of Texas(Austin), Bureau of Economic Geology, Report Krohn, J. P, and Slosson, J. E.,1976, Landslide Potential in the United States: of Investigations no. 198, pp. 32-45. Califomia Geology, v. 29, pp. 224237. Gustavson, R. C., and Finley, R. J., 1985,Late Cenozoic geomorphic evolution of Lambert, P. W., Hawley, J. W., and Wells, S. G., 1982, Supplemental road-log the TexasPanhandle and northeastem New Mexicecase studies of structural segment III-S: urban and environmental geology of the Albuquerque area: New control on regional drainage development: Univ of Texas(Austin), Bureau of Mexico GeologicalSociety, Guidebook to 33rd Field Conference,pp.97-124. Economic Geology, Report of Investigations no. 1118,r{2 pp. Larsen, S., and Reilinger, R., 1983, Recent measurementsof crustal deformation Guzetti,F., andBrabb, E.E.,1987, Mapshowinglandslidedepositsinnorthwestern related to the Socorro magma body, New Mexjco: New Mexico Geological Society, New Mexico: U.S. Geological Suruey, Open-file Report 87-70, 2 sheets, scale Guidebook to 34th Field Conference,pp. ll9-1.27. 1:500,000. Limburg, E. M., 1990,Recent and potential volcanism of New Mexico: Unpublished Hacker, L. W., 9n, Soil suruey of Bernalillo Counw and parts of Sandoval and MS researchpaper, New Mexico Institute of Mining and Technology,149 pp. Valencia Counties, New Mexico: United States Department of Agriculture, Soil Lovelace,A.D.,19T6,Stabilizationof areactivatedlandslidenearWagonMound ConseruationService, 101 pp. I maps. on Interstate 25: New Mexico Geological Society,Guidebook 27th Field Confer- Haneberg, W. C., 199o,Use of seismicreflection profiles to characterizesoil defor- ence, PP. 2n-279. mation associatedwith earth fissuresand ground-water withdrawal near Deming, Lovelace, A. D., Bennett, W. D., and Lueck, R. D., 1982,Test section for the sta- New Mexico: New Mexico Bureau of Mines and Mineral Resources,Open-file bilization of collapsiblesoils on Interstate25, Prolect 1-025-4(58)243, Algodones, Report367, 19 pp. New Mexico: New Mexico State Highway DePartment, GeotechnicalSection, Haneberg, W. C., 1991,,Pore pressure diffusion and the hydrologic response of Materials Laboratory Bureau, Report MB-RR-83-1, 27 pp nearly saturated, thin landslide deposits to rainfall: Journal of Geology,v.99, pp. Machette, M. N., f986, History of Quatemary offset and Paleoseismicityalong the 886-892. I-a Jenciafault, central Rio Grande rift, New Mexico: Bulletin of the Seismological Haneberg,W. C.,1992, Thin-plate analysisof regional land subsidenceand fissuring Society of America, v.76, pp.259272. in the Mimbres basin, southern New Mexico (abs.):Geological Society of America, Machette, M. N., 1987, Preliminary assessmentof paleoseismicityat White Sands Abstracts with Programs, in press. Missile Range, southem New Mexico: evidencefor recencyof faulting, fault seg- Haneberg,W. C., Reynolds,C. 8., and Reynolds,l.8.,1991, Geophysicalcharac- mentation, and repeat interoals for maior earthquakesin the region: U.S. Geo- terization of soil deformation associatedwith earth fissuresnear San Marcial and logicaf Suruey, Open-file Report 87-M4, 46 pp. Deming, New Mexico; in Johnson, A. I. (ed.), Land subsidence (Proceedings, Machette, M. N., 1988, Quatemary movement along the La Jencia fault, central Fourth Intemational Symposium on Land Subsidence,Houston, Texas,May 12- New Mexico: U.S. GeologicalSuruey, ProfessionalPaper 144O,82pp. 18, 1991):International Associationof Hydrological Sciences,Publication no. 2(F, MacMillan, J. R., Naff, R. L., and Gelhar, L. W., 1976, Prediction and numerical pp.27n80. simulation of subsidenceassociated with proposed ground-water withdrawal in Haneberg, W. C., and Tripp, G., 190, Engineering geologic investigation of an the Tularosa Basin, New Mexico (ProceedingsSecond International Symposium irrigation-induced debris flow near Cordova, Rio Arriba County, New Mexico: on Land Subsidence,Anaheim, Califomia, December13-17,7976): Intemational New Meico Bureau of Mines & Mineral Resources,Open-file Report 371, 80 pp. Association of Hydrological Sciences,Publication no. 121, pp. 500-508. Haneberg, W. C., and Tripp, C.,1991, An irrigation-induced debris flow in northern Mclemore, V. T., and Hawley, l. W., 1988,Preliminary geologicevaluation of radon New Meyico: Bulletin of the Association of Engineering Geologists, v. XXVIII, availability in New Mexico: New Mexico Bureauof Mines and Mineral Resources, pp.359-374. Open-file Report 35, 30 pp. Hansen, A., l9U, Landslide hazard analysis; in Brunsden, D., and Prior, D. B. Menges, C. M., 7987,Temporal and spatial segmentationof Plio-Quatemary fault (eds.), Slope instability: Chichester,UK, fohn Wiley & Sons, pp.523-602. rupture along the baseof the westem Sangrede Cristo mountain front, northem Hawley, J. W., and Longmire, P. A,.,7997, Site characterizationand selection; In New Mexico; ln Menges, C., Enzel, Y., and Hanison, B. (eds.), Quaternary tec- Reith, C. C., and Thomson, B. M. (eds.), Desertsas dumps?: Albuquerque, Uni- tonics, landform evolution, soil chronologiesand glacial deposits-northern Rio versity of New Mexico Press, pp.57-99. Grande rift of New Mexico: Friends of the Pleistocene-Rocky Mountain Cell, Hawley, J. W., and Love, D. W., 1981,Overuiew of geology as related to environ- Field Trip Guidebook, October 8-11, 1987,pp.71-93. mental concernsin New Mexico; ln Wells, S. G., and Lambert, W. (eds.), Envi- Menges, C. M., 799{J,Late Quaternary fault scarps,mountain-front landfoms, and ronmental geologyand hydrology in New Mexico:New Mexico GeologicalSociety, Pliocene-Quaternarysegmentation on the range-bounding fault zone, Sangrede SpecialPublication no. 10, pp. 1-10. Cristo Mountains, New Mexico; in E.L- Krinitzsky, E. L., and Slemmons, D. B. Hawley, J. W., and Love, D. W, 1991,Quaternaryand Neogenelandscapeevolution: (eds.), Neotectonics in earthquake evaluation: Geological Smiety of America, a transect across the Colorado Plateau and Basin and Range Provinces in west- Reviews in Enginering Geology VIII, pp. 131-155. centralNew Mexico: New MexicoBureau of Mines and Mineral Resources,Bulletin National ResearchCouncil, 1985, Reducing losses from landsiding in the United 137,pp.705-1.48. States:National AcademyPress,41 pp. Hays, W. W., editor, 1981,Facing geologic and hydrologic hazards:U.S. Geological National ResearchCouncil, 191, Mitigating losses from land subsidencein the Suruey, ProfessionalPaper 1240-8, lE pp. United States:National Academy Press,58 pp. [?

Nm Mexico Geology August 1992 )l Nilsen, T. H.,l9tl6, Relative slope-stabilitymapping and land-use planning in the San_Franci.scoB-aIfgi9", Califomia; ir Abrahahs, A. D. (ed), Hillilope pr5""r.es ilewMexico Geological Society Boston, Allen & Unwin, pp. 389-413. 1992Field Conference Nortfuop, S. A , 1976,New Mexico's earthquakehistory l,M9-1973;in Woodward, L. A., and Northrop, S. A. (eds),Tectonici and mineril resourcesof southwestem SanJuan Basin lV North America: New Mexico Geological Society,Special publication no 6, pp. n-87. Osterkamp, W.X., Fenton, M. M., Gustavson,T. C., Hadley, R. F.. Holliday, V T., Morrison, R. 8., and Toy, T. f ., l98Z Great plains; in Gral W. L. (ed.), Geoirorphic systems of North America: Geological Society of America, Centennial Spirial Volume 2, pp. 163-210. Radbruch-Hall, D. H., Colton, R. 8., Davies, W. E., Skipp, B. A., Lucchitta, L, and Varnes, D. f., 1981,Landslide overview map of the conterminous United States: lj.S _ _c99log!calSuruey, ProfessionalRaper it83, 25 pp., scale1:7,500,0ffi. Rahn, P H., 1986,Engineering Geology: Elsevier,589 pp. Reiche,P., 1937,The Toreva-b6ck+ JisHnctive landsli'd'etype: Joumal of Geology, v.45, pp.538-548. Reimers,_R.F., 1?16,Geology, gollapsemechanisms, and prediction of collapsible soil in El Llano, New Mexico:New Mexico Bureauof Minei and Mineral Resoirces, Open-file Report 239, 249 pp. Rex, H. , 1991,Sourcebook foi New Mexico geographicinformation: New Mexico Geographic Information Council (available-from New Mexico Bureau of Mines and Mineral Resources,Socorro), 36 pp. Robinson, G. D., and Spieker, A. M., editors, 1978,Nature to be commanded .: - U.S._Glglogical Survey, ProfessionalPaper 950, 95 pp. Salyards,S. L.,191, A preliminary assessmentof the seismichazard of the southern Rio Grande rift, New Mexico: New Mexico GeologicalSociety, Guidebook to 42nd Field Conference, pp. 199)02. Sanford, A., 1983, Magma bodies in the Rio Grande rift in central New Mexico: New Meico Geological Society, Guidebook to 34th Field Conference, pp 723_ tE.

The 43rd Field Conferencewill be held September30-October 3, 1992in northwestern New Mexico. The conferencewill focus on the varied geology of the region, especially Laramide tecton- ism and sedimentation in the San fuan Basin; sequencestratig- raphy of Upper Cretaceousstrata; the Cretaceous-Tertiary boundary; coal and coalbed methane resources;the Rio Puerco necks of the Mt. Taylor volcanic field; geomorphology and hy- drogeology; and Late Cretaceousand early Tertiary paleontology. Headquarters for each trip leg will be in Cuba, New Mexico, a small town at the foot of the Nacimiento Mountains. The field conference will journey by caravan to the badland country of the southern San |uan Basin, the spectacularvolcanic necks of the Rio Puerco region, and along the eastern margin of the Colorado Plateau north to Abiquiu Dam. Seager.W. R , and Mack, G. H., 7991,Geology of Garfield quadrangle, Siena and Trip participants will arrive on Wednesday,September 30, for Dofla Ana Counties, New Mexico: New Mexico Bureau of Minei and Mineral the opening-night icebreaker,hosted by the New Mexico Geo- Resources,Bulletin 128, 24 pp. logical Society. Shaw, D., and Johnpeer,G., f985a,Ground subsidencenear Espaiola, New Mexico: New Mexico Geology, v.7, pp.32-M. Day one, October 1, features travel south on NM-44 to San Shaw, D., and Johnpeer, G., 1985b,Ground-subsidence study near Espaiola and Luis, west to the Rio Puerco valley near Cabezon Peak, north recommendations for construction on collapsible soils: New Mexico beology, v. along the southern edge of Mesa Portalesto TorreonTrading Post, 7, pp.59-62. and then northeast to Cuba. An evening barbecuewill follow the first day's trip. Day two, October 2, begins by journeying west on NM-44 past Lybrook to Huerfano Trading Post, south on NM-371 to the De- Na-Zin and Bisti badlands and the Fossil Forest, then retracesthe route back to Cuba. The annual banquet will be held in Cuba on Watson, R. A., and Wright, H. E , Jr., 1963, Landslides on the east flank of the Thursday night with Dr. Dag Nummedal of Louisiana State Uni- Chuska Mountains, northwestem New Mexico: American Journal of Science,v. versity as speaker. 261, pp 525-5/a. Day three, October 3, is by caravan north on NM-96 to Llaves, Wells, S. G., and tambert, W., editors, 1981,Environmental geology and hydrology then east on NM-112 to Abiquiu Dam. Participants in New Mexico: New Mexico Geological Society,Special Fubhcitlon tO, iiZ may leave the PP. "o. conferenceon NM-112 east toward SantaFe or west toward Cuba Williams, J. L, 1986,editor, New Mexico in maps: Albuquerque, University of New or on NM-44 toward Albuquerque. Mexico Press, 409 pp. L_.1 Principal field-trip leaders are Brian Brister, Gretchen K. Hoff- man, Adrian P. Hunt, David W. Love, Spencer G. Lucas, Larry N. Smith, and Thomas E. Williamson. The guidebook is edited by Adrian P. Hunt, Barry S. Kues, SpencerG. Lucas,and Thomas E. Wiliamson. We look forward to your attendance at the t992 New Mexico GeologicalSociety fall field conference.For more information con- tact Orin f. Anderson, Registration Chairman, New Mexico Bu- reau of Mines and Mineral Resources,Socorro, NM 87801,(505) 835-5L22. -Spencer G. Lucas,Thomas E. Williamson Field ConferenceCo-Chairmen

August 1992 New Mexim Geology