Mountains Southwest Research Articles

Planning Roads for Darfur, Sudan

The province of Darfur, Sudan, has been in the news for several years because of civil unrest and the suffering of its population. The Darfur region is defined as the triangular area connecting El Fasher, Nyala, and Geneina (on the Chad border). The road system is rudimentary at best. Transport development in Darfur is more difficult than in other regions of the country because of its location at the western extreme of the country and its geologic complexity. Data are presented from the Sudan Road Survey, which is one of the best sources of geotechnical data needed for the planning of low-volume roads in Sudan. The fieldwork took 18 months and covered the central and northern portions of the country, from the Ethiopian border to westernmost Darfur and from the Nuba Mountains southwest of Khartoum to the Egyptian border. The aim was to produce basic engineering data for road design, including estimation of construction and maintenance costs. In addition, the original field logs contain personal commentary that provides insight into the difficulty of conducting field research in Sudan at that time.

China Subregional Avian Endemism and Biodiversity Conservation

Richness of endemic species is considered important for biodiversity conservation and avifaunal regionalization, but no detailed studies concerning the subregional endemism have yet been done in China. Here we investigate the assemblage of China avian endemics of each avifaunal subregion, and analyze the faunal subregional species diversity, subspecific differentiation, and their relationships. The endemic species richness is found to be the highest in the Southwest Mountainous subregion where 60 species account for 57.1% of China’s 105 endemics. Seventy seven species accounting for 73.3% are monotypic. Twenty eight species (26.7%) occurred in only one subregion; the mean was 3.14±1.929 subregions, while 3 species were found widespread over 8 subregions. The number of species distributed only at one specific subregion (EOSR) is the highest in Taiwan subregion. The Southwest Mountainous subregion has the second highest EOSR and the highest richness of monotypic species, but the ratio of numbers of monotypic species or EOSR to the numbers of its subregional overall endemic species is not high in this subregion (68.3%; 10.0%). On the contrary, Taiwan subregion does not have higher richness of overall endemic species and monotypic species, but the EOSR is the highest, while the ratio of numbers of monotypic species or EOSR to the numbers of its subregional overall endemic species is also the highest among all subregions (76.2%; 71.4%). From the evidence of comparing subregional distribution of overall endemic species, EOSR, monotypic species and subspecific diversification, we may conclude that geographical isolation might be the main effect factor contributing to both subspecific diversification and avian subregional endemism in China. The higher endemic and monotypic richness in the Southwest Mountainous subregion may also indicate that the subregion’s avifaunal evolutionary and ecological isolation results from the highly diversified habitats and geographical environments as well as the historical effects from the primitive avifauna.

Reliable Maps of Lightning Thunderstorms for Saudi Arabia

The main objective of this research is to develop reliable maps of isokeraunic level (thunderdays/year, TD) for the country on annual and seasonal bases. New annual thunder day maps for Saudi Arabia are presented. The results in this paper are based on data and records of thunderstorm incidences in Saudi Arabia recorded by the Presidency of Metrology and Environment. These are compared with data from power system fault records and with NASA satellite data. These new maps indicate the location, frequency, and intensity of thunderstorms. Such information is useful for engineers concerned with the design and operation of transmission and distribution lines in the country, and for the more general design of lightning protection systems. Thunderstorms are most frequent in the southwest mountains in the country, reaching a maximum TD of 97; the average TD for the whole country is 26.

Distribution of landslides in southwest New Zealand

This study examines the size distribution of a regional medium-scale inventory of 778 landslides in the mountainous southwest of New Zealand. The spatial density of mapped landslides per unit area can be expressed as a negative power–law function of Landslide area AL spanning three orders of magnitude (∼10−2–101 km2). Although observed in other studies on landslide inventories, this relationship is surprising, given the lack of absolute ages, and thus uncertainty about the temporal observation window encompassed by the data. Large slope failures (arbitrarily defined here as having a total affected area AL>1 km2) constitute 83% of the total affected landslide area ALT. This dominance by area affects slope morphology, where large-scale landsliding reduces slope angles below the regional modal value of hillslopes, ϕmod∼39°. More numerous smaller and shallower failures tend to be superimposed on the pre-existing relief. Empirical scaling relationships show that large landslides involve >106 m3 of material. The volumes VL of individual preserved and presumably prehistoric (i.e. pre-1840) landslide deposits equate to 100–102 years of total sediment production from shallow landsliding in the respective catchments, and up to 103 years of contemporary regional sediment yield from the mountain ranges. Their presence in an erosional landscape indicates the geomorphic importance of landslides as temporary local sediment storage.

English

An evaluation of groundwater conditions in the vicinity of coal mines near Colstrip, Montana was conducted in 2001 as part of a cumulative hydrologic impact analysis. This analysis was required due to permitting activities associated with an expansion of the Rosebud Mine. Active coal mining operations at the Rosebud mine have expanded outward as low-cover coal is sought. Much of the remaining, unmined coal nearest to Colstrip and the adjacent coal-fired power plant is relatively high-cover coal, so mining has slowed in the interior area of the coal deposit in favor of lower-cost mining at the edges. Because the interior, high cover coal will eventually be mined according to mine plans, presently inactive pits remain open for future use. As the mine expands, additional information gained through hydrologic monitoring contributes to and increases the understanding of the groundwater system and how it is affected by mining. Overall, groundwater flow directions are similar to pre-mine conditions. Where coal has been mined out, mine pit backfilled spoil maintains the groundwater flow formerly occurring in the coal seam. However, groundwater head distribution has changed significantly in some areas, and some of these head differences may be retained in the post mining groundwater environment. As mining operations have expanded, data suggests recharge to the principle coal seams may be more localized than was previously thought, and groundwater recharge from the Little Wolf Mountains southwest and upgradient of the coal deposit is limited. Drawdown of groundwater levels in the McKay coal seam, which lies beneath the mined Rosebud coal exceeds that observed in the Rosebud coal at many sites. While this phenomenon has previously been attributed to the presence of inadequately plugged coal exploration boreholes, data suggests this explanation is less likely near recent mining activities.

Future climate change, the agricultural water cycle, and agricultural production in China

Climate change would have a major impact on the hydrological cycle and consequently on available water resources, the potential for flood and drought, and agricultural productivity. In this study, the impacts of climate change on the agricultural water cycle and their implications for agricultural production in the 2020s were assessed by water-balance calculations for Chinese croplands. Temporal and spatial changes in potential evapotranspiration, actual evapotranspiration, soil-moisture, soil-moisture deficit, yield index, and cropland surface runoff under the baseline climate and a HADCM2 general circulation model (GCM) climate-change scenario were mapped on a grid of 0.5° latitude/longitude resolution. According to the analysis, agricultural water demand in south China is projected to decrease generally, and the cropland soil-moisture deficit would decrease due to climate change. However, in north China, agricultural water demand is expected to increase, and the soil-moisture deficit would increase generally. The changes in the water resources would have consequent impacts on the yield index. Cropland surface runoff during the growing period is expected to increase on some sloping croplands in the southwest mountain areas and in some areas along the south coast. These changes would have important implications for agricultural production. Particularly the rain-fed crops in the north China plain and northeast China would face water-related challenges in coming decades due to the expected increases in water demands and soil-moisture deficit, and decreases in precipitation.

The critical regions for conservation of rare and endangered plant species diversity in Zhejiang Province

Zhejiang Province is rich in plant resources. There live a total of 215 families, 1196 genera and 3283 species of wild vascular plants, including 49 genera endemic to China and 2000 species endemic to Zhejiang. Many species have become rare and threatened, and therefore, should be conserved as soon as possible. However, these rare and endangered plant species are not distributed evenly. Attention should be given to the regions where more plant species deserving protection exist. According to plant diversity, species richness of rare and endangered plants, and their individual quantitative features, imperiled status, and the distribution of endemic plant in Zhejiang Province, seven critical reserve regions for plant species diversity protection are suggested. They are northwest mountains (centered around Xitianmu Mountain), west mountains (centered around Gutian Mountain), southwest mountains (centered around Jiulong Mountain), south mountains (centered around Fengyang and Baishanzu Mountains), east mountains (centered around Kuocang Mountain), east hills (centered around Tiantai hill land), and Zhoushan Archipelago (centered around Putuoshan Island). Measures to protect plant diversity in Zhejiang are suggested.

Tectonic heredity and tectonic wedging along an oblique hanging wall ramp: The southern termination of the Misty thrust sheet, southern Canadian Rocky Mountains

The Misty Range is a homoclinal, southwest-dipping panel of Paleozoic carbonate rocks in the Canadian Rocky Mountains southwest of Calgary that has been juxtaposed against underlying Mesozoic siliciclastic rocks along the northeast-verging Misty thrust fault. At the south end of the Misty Range, a steep, oblique ramp marks an abrupt southward change along the hanging wall of the Misty thrust, from a detachment zone in the Upper Devonian Palliser Formation to another detachment zone in the Jurassic Fernie Group. This 2-km-high ramp is expressed, in the hanging wall rocks, as a large, oblique, southeast-plunging fold. A west-verging back-thrust that rises from a detachment zone in the Mississippian Mount Head Formation extends across the hanging wall ramp fold and is truncated by the Misty thrust. The Misty thrust evidently propagated southward as an oblique tectonic wedge into this detachment zone, forming a “triangle zone” structure with the back-thrust as the roof thrust. As displacement on the Misty thrust increased, and the hanging wall ramp of the Misty thrust moved into the triangle zone, the back-thrust was progressively back-folded and became convex. Subsequently, the lower part of the back-thrust was partly overridden by the Misty thrust and became overturned, before becoming detached and incorporated in the Misty thrust sheet. The configuration and evolution of the tectonic wedge and the oblique hanging wall ramp provide a natural prototype for the interpretation of ramps that mark the lateral terminations of oil and gas reservoir structures in the Foothills belt, but which are concealed by overlying deformed Mesozoic rocks.

Electrical conductivity variations around the Palmdale Section of the San Andreas Fault Zone

Our analysis of a decade of observations from the Palmdale California telluric array is presented. The array is a system of large‐scale telluric field measurements used for the passive monitoring of electrical conductivity variations over a large region centered over the San Andreas Fault Zone northeast of Los Angeles. Since 1985, systematic changes in the relationships between the telluric field measurements around the array have been observed. These changes amounted to 1% to 2% by the time the array was closed down in 1989, with the fields measured along the fault and northeast of the fault showing signal decreases relative to the fields southwest of the fault. Because of the possible implications of these changes for conductivity variations related to tectonic activity on the San Andreas, we have attempted to sort out the geography of the zones that could cause the changes. The simplest, though nonunique, interpretation of the observed variations in the telluric relationships is a steady increase in the conductivity of the lower crustal region of the fault zone. From two‐dimensional models of the telluric response around the array, we infer that an increase of about 60 milli‐Siemens in the conductance of the lower crustal fault zone could account for the changes seen over the period 1985 to 1989. Assuming changes were in a kilometer‐wide zone and that the lower crustal fluids were very conductive, this could represent a strain of about 0.4 × 10−6. The surface strain would be much smaller and would be lost in surface strain noise. Because of the possibility that fluid pressure changes are involved, these small strains could still be significant for earthquake cycle phenomena. Alternatively the observed changes could have been produced by increases in the conductivity of the upper crust of the Mojave Desert, northeast of the fault, or by decreases in the conductivity of the upper crust in the San Gabriel Mountains southwest of the fault To produce the observed telluric changes, however, the additional conductivity and the associated strain changes would have to be much larger. The strain needed to accommodate the increased conductivity on the Mojave side would have to be of the order of 6 × 10−4, which seems unrealistically high. Smaller strains could account for conductivity changes in the San Gabriel Mountains, but these strains would have to be compressive. Water‐level changes are not considered to be a possible cause of the conductivity changes because the measurement scale is much larger than the typical scale of water level changes, and no seasonally correlated changes in the telluric fields were observed.

Prehistoric Rock Avalanches in the Olympic Mountains, Washington

Rock avalanches blocked streams in the Olympic Mountains southwest of Puget Sound during the past few thousand years. Limiting radiocarbon ages indicated that three or four of six avalanches occurred from 1000 to 1300 years ago or shortly thereafter. Most of the dates were from the outer preserved rings of trees drowned behind avalanche dams. These three or four avalanches may be coeval not only with one another but also with abrupt tectonic deformation in western Washington. No rock avalanches in the Olympic Mountains are known to have resulted from storms or earthquakes during the past century. The avalanches strengthen the case that a large prehistoric earthquake occurred in the Puget Sound region.

Mountains, Land, and Kin Networks: Burkes Garden, Virginia, in the 1840s and 1850s

BURKES GARDEN IS AN OVAL LIMESTONE VALLEY OF ABOUT FORTY SQUARE miles on the southeast edge of Tazewell County in mountain southwest Virginia. The highest valley in Virginia, it is completely surrounded by the unbroken wall of Garden Mountain, which contains only one natural opening, a water gap cut by Wolf Creek to the north. This natural barrier kept the Garden from being actively settled until early in the nineteenth century, although whites first explored it and entered land claims in the 1750s. The topography of Burkes Garden necessitated community cooperation and limited agricultural development. Despite its geographical isolation, the Garden was touched by the outside world, primarily in the form of county courts and officials and a thriving livestock market. A speculative market in real property divided society into the landed and the landless and enabled the members of a recognized elite to hold power over many of their tenant neighbors-despite rhetoric, then and since, about Appalachian egalitarianism. Commerce in cattle intersected neighborhood commodity exchange rooted in credit and barter. Husking bees coexisted with suits for debt, kinship obligations with competition for grazing land. The people of antebellum Burkes Garden lived partly in a traditional world imposed and protected by the mountains and partly in a modern world of courts and capitalism. Burkes Garden, then, was neither completely isolated nor structurally egalitarian. Its landless deferred to the landed and its poor to the less poor, but the differences in behavior and social power were not nearly as great as the differences in wealth and landholding might lead one to expect. Through kin and neighborhood networks, the Appalachian people maintained an egalitarian identity in a manifestly unequal society. In describing societies in which landlord-tenant relations are central, scholars often explain social dynamics in terms of patron-client

Die Weiden (Salix) der Sektion Chamaetia und das Problem der Entstehung der arktischen Flora )

Summary The Arctic-Alpine willow section Chamaetia is composed of 4 species: Salix reticulata, S. vestita S. nivalis, S. erythrocarpa. Until now this section has been regarded as a taxonomically isolated one, its relationships being quite obscure. Author’s investigation of willows of the mountainous Southwest China — which is the renowned conservation centre of old Tertiary relics of deciduous flora — has revealed that some of these Chinese willows, and especially those placed by Chou et al. (1984) into sections Magnificae and Psilostigmatae, are very close to species of the section Chamaetia. The nearest relative seems to be S. phanera , which may even be placed, without much hesitation, with the section Chamaetia. Thus we may conclude that the contemporary section Chamaetia descended from the primitive ancient-Tertaiary stock directly, and not via any boreal groups. Whether other Arctic and Arctic-Alpine willows have a similar origin, remains to be investigated

Mineral Concentrations of Black-Tailed Deer Diets in California Chaparral

The monthly level of phosphorus (P), sulfur (S), calcium (Ca), magnesium (Mg), and potassium (K) in the diet of black-tailed deer (Odocoileus hemionus columbianus) in mixed-age chaparral of California was determined during 1985-86. Forage samples were harvested by hand and analyzed using standard analytical methods. Annually, dietary concentrations averaged 0.16, 0.11, 0.49, 0.25, and 0.85% for P, S, Ca, Mg, and K, respectively. Levels of P and S were below the recommended minimum requirement during most months. In contrast, levels of Ca, Mg, and K were adequate during most months. To improve forage quality in mixed-age chaparral managers can implement range improvement practices, such as prescribed burning and chemical and mechanical brush control. J. WILDL. MANAGE. 52(1):37-41 Columbian black-tailed deer are an important big game animal in California. In some habitats deer densities may be low due to forage of poor quality. Most studies assessing the nutrient value of deer forage have been concentrated in the Southwest (Urness et al. 1971, Varner et al. 1977, Everitt and Gonzalez 1981) and Rocky Mountain region (Short et al. 1966, Tew 1970, Wallmo et al. 1977). In California monthly levels of forage quality of selected chaparral species have been determined (Bissell and Strong 1955, Kie 1986), but the relationship between forage quality and deer diet has usually been discussed only in terms of crude protein (Taber 1956, Taber and Dasmann 1958). We report the mineral concentrations of blacktailed deer forage in mixed-age chaparral of California. Forage components were evaluated monthly for P, S, Ca, Mg, and K to identify periods of maximum and minimum forage quality and to detect real or potential problems relating to deer management in mixed-age chaparral. 1 Present Address: EG&G Energy Measurements, % NPR-1, 35R Warehouse, P.O. Box 127, Tupman, CA 93276. This content downloaded from 157.55.39.116 on Sun, 18 Sep 2016 06:41:48 UTC All use subject to http://about.jstor.org/terms 38 BLACK-TAILED DEER DIETS * Scrivner et al. J. Wildl. Manage. 52(1):1988 Table 1. Mean percent mineral compositiona (dry-wt basis) of plant species sampled mid-monthly from June 1985 to July 1986 on the University of California Hopland Field Station.

Inshallah Gurbah Ast: “God Willing, It's A Cat”

When Dihkhuda published his poem Inshallah gurbah ast (“God willing, it's a cat”) in 1933, he created quite a stir in Iranian literary circles. The great scholar Muhammad Qazvini, for example, was inspired to call the poem “without a doubt one of the masterpieces of modern literature.” Even a poem of lesser quality, however, would have been the cause of some wonderment, for Dihkhuda's pen had been silent for nearly fifteen years. After transforming Persian prose during the Constitutional Revolution of 1905 with his column Charand parand (Chit-Chat), Dihkhuda gave up writing satirical social commentary in the tumult and disillusionment of the First World War. While sitting out the war in the mountains southwest of Isfahan, Dihkhuda occupied himself with the only book he had available—a Larousse French Dictionary.

Effects of Abiotic Disturbance on Coexistence of Predator‐Prey Fish Species

Behavioral responses of animals to large—scale abiotic disturbance are poorly known. Organisms living in habitats with frequent perturbations may evolve behaviors that minimize the impact of, or exploit, the disturbance. Organisms from environments that have fewer or different perturbations should not evolve these behaviors. The Sonoran topminnow (Poeciliopsis occidentalis) a poeciliid fish native to the arid American southwest, and the mosquitofish (Gambusia affinis), a morphologically similar poeciliid introduced from the mesic central and eastern United States, occur sympatrically in a few Arizona localities. Since flash floods of the mountainous Southwest are quantitatively and qualitatively different from the typical spring floods of mesic lowland drainages, I predicted that introduced G. affinis populations would incur greater losses during Southwestern floods than would native P. occidentalis. This was supported by preflood and postflood populations surveys in a natural habitat and by subsequent laboratory simulations of floods. The native species apparently possesses innate behaviors, such as quick response and proper orientation to high discharge, that allow its persistence under flash flood conditions. Mosquitofish show little such behavior and are more easily displaced by floods. Mosquitofish typically extirpate topminnows from native habitats via predation within 1—3 yr after introduction. Replacement is most rapid in localities that rarely or never flood, while long—term coexistence may occur in frequently flooded habitats. Abiotic disturbances may promote coexistence by periodically reducing population sizes of the exotic predator before the native prey species is eliminated. This hypothesis is consistent with data from a variety of other Arizona aquatic systems containing communities of native prey and introduced predatory fishes.

Late Cenozoic History of Safford-San Simon and Bonita Creek Structural Basins, Graham County, Arizona: ABSTRACT

Sedimentary rocks of the interconnected Safford-San Simon (S-SB) and lower Bonita Creek (BCB) basins are separated into: (1) lower Miocene volcaniclastic conglomerate, (2) upper Miocene? to Pleistocene? Gila Conglomerate, and (3) Quaternary alluvium and surficial deposits. The volcaniclastic conglomerate is locally interbedded with andesite and 19-Ma ash-flow tuff in BCB and is part of the bed rock deposited prior to formation of structural basins by Basin and Range extensional tectonics. The Gila Conglomerate consists of more than 1,200 m (3,900 ft) of basin-fill sedimentary rocks. Where exposed, most of the lower units are locally derived alluvial-fan deposits. Upper units of the Gila (Pliocene to lower Pleistocene?) include lacustrine beds interbedded with deposits of low-gradient alluvial fan covering 730 km2 (280 mi2) from its apex at the mouth of Bonita Creek, southwestward across the width of the S-SB. Thick sequences of halite and gypsum penetrated in wells in the S-SB indicate playa deposits at depth. Red granite clasts in the fan deposits indicate that Bonita Creek had eroded headward to the upper BCB and captured streams draining the Point of Pines area. The youngest sediments are chiefly Quaternary alluvium deposited after the Gila River developed through-flowing drainage. The initial course of the Gila River was along the north side of the low-gradient fan. This course disrupted the depositional balance of streams draining the Pinaleno Mountains southwest of the S-SB and caused deposition of range-front alluvial fans 1 0 m (390 ft) thick. These fans were abandoned as the Gila River migrated to the center of the basin and are now spectacularly exposed as erosional remnants. End_of_Article - Last_Page 938------------

Phytogeography of the tropical north-east African mountains

The tropical north-east African mountains are tentatively divided into four phytochoria, the formal rank of which is not defined. The division is based on patterns of distribution and endemism in the region. The recognition of a distinct Afromontane phytochorion is now well established (Chapman White, 1970; Werger, 1978; White, 1978). However, there is still very little information on the phytogeography of the individual mountains or mountain systems. This study hopes to fill a little of the gap by analysing distribution patterns and patterns of endemism in the flora of the tropical north-east African mountains. The north-east African mountain system is the largest in tropical Africa (see e.g. map in White, 1978). At the core of this system is the large Ethiopian massif, around which are located various mountains and mountain chains. These include the Red Sea Hills in the Sudan, the mountain chain in northern Somalia, the south-west Arabian mountains, and the Imatong mountains of south-east Sudan. The latter are often referred to the East African mountain system (White, 1978) but. as I will point out later, they also have a close connection with the south-west highlands of Ethiopia. The paper presents some results of my study of the mountain flora of tropical north-east Africa, particularly the forest species. Where no source is indicated, the data are from my own unpublished studies.

A Late Stone Age Site in the Erongo Mountains South West Africa

The main object of this paper is to draw attention to the existence of Late Stone Age sites in South West Africa where perishable organic remains are preserved, and in particular to the ‘Big Elephant Cave’, discovered by Dr E. R. Scherz in the Erongo Mountains.These lie some 10 to 15 miles north-north-east of Usakos, at approximately 21° 40′ S., 15° 40′ E., in a region of open grass steppe with stands of thornbush, mainly Acacia, with low sclerophytic scrub supported by an annual rainfall of between 150–200 millimetres. These mountains rest on Basement Complex rocks and consist of Karroo sediments through which have been introduced granites of post-Karroo Age. The western face of the Erongo forms the edge of the plateau escarpment, and looks out to the Namib Desert and the Atlantic Ocean.The cave, to which we were conducted in May, 1959, by Dr Scherz, is situated in a commanding position on a kopje of rounded granite boulders near Ameib. It was first shown by its discoverer to the Abbé Henri Breuil when he was copying the Erongo rock paintings, but no study of the settlement was made and it was not revisited in the interim. Although the name ‘Big Elephant Cave’ has been adopted from Dr Scherz, it is, in fact, a deep rockshelter rather than a cave. It contains no paintings, but a line of male and female figures, in faded red paint, is drawn low down on a protected rock at the north side of the kopje. These have been published by the Abbé Breuil.

Geology of Corona South Quadrangle: ABSTRACT

The Corona South Quadrangle lies in the northern part of the Peninsular Ranges. It contains the northwest end of the Elsinore trough which marks the trace of the Elsinore fault zone and trends northwestward across the center of the quadrangle. The Chino fault diverges north-northwestward from its apparent junction with the Elsinore fault near the eastern margin of the quadrangle. The oldest rocks, those of the Triassic Bedford Canyon formation, are meta-sedimentary in character, and occur mainly in the Santa Ana Mountains southwest of the Elsinore fault. Here they have been intruded by late Mesozoic plutonic rocks of the Southern California batholith and in a few places are unconformably overlain by Jurassic(?) volcanic rocks. Northeast of the Elsinore fault is a succession of sedimentary rocks, several thousand feet thick, which includes rocks of Upper Cretaceous through Quaternary age. These units are of types found on the west in the Los Angeles Basin. The dominant structural features are the Elsinore and Chino zones of high-angle reverse dip-separation faults and a synclinal trough which extends from the Puente-Chino Hills southeastward beyond Corona and lies nearly parallel with and northeast of the Elsinore fault. The surface distribution of Cretaceous sedimentary rocks indicates a probable minimum vertical displacement of 1,500 feet along the Elsinore fault southwest of Corona, whereas on the southeast a displacement of more than 5,000 feet is suggested by the difference in elevation of the basement complex on opposite sides of the fault. In post-Pliocene time, and perhaps throughout their history, the Elsinore and Chino fault zones have had an apparent high-angle reverse sense of movement. Large lateral displacement is not demo strated in the mapped area. In the Corona area the Elsinore trough is probably a faulted syncline. Mining operations, especially for clay, crushed and broken stone, and glass sand, have been End_Page 254------------------------------ carried on since the late nineteenth century. Repeated though unsuccessful attempts have been made to find petroleum. Records indicate 15 wildcat oil wells have been drilled within the quadrangle since 1925. Of these wells, 12 were put down in the period 1949-56. Several wells may have encountered noncommercial gas and oil shows, but there has been no sustained production. End_of_Article - Last_Page 255------------

Bouguer anomaly map of New Zealand

Summary The Bouguer map of New Zealand exhibits two major negative gravity anomalies. The Rangitikei-Waiapu Anomaly, which intersects tne axial ranges of the North Island, indicates a crustal downwarp which is not in isostatic equilibrium. This anomaly is closely parallel to the zone of intense seismicity, to the Taupo-White Island volcanic belt, to the Kaimanawa-Huiarau-Raukumara Ranges, to the thick Upper Pliocene sediments, and to the Hikurangi Trench; and it appears to be an expression of an active tectonic belt related to the Tonga-Kermadec-Hikurangi Trenches. The Rimutaka-Ruahine axial ranges are apparently not underlain by mountain roots. The Alpine Anomaly in the South Island is considered to be the gravitational expression of the crustal roots of the Southern Alps and the mountains south-west of Blenheim; the magnitude of the anomaly suggests that this region is' approximately in isostatic equilibrium.