Summit Ridge Research Articles

197 Trace Mineral Source Affects Haircoat Characteristics and Shedding in Cats

Abstract Trace minerals have a pivotal role in maintaining skin health and haircoat characteristics in companion animals. The objective of the current study was to evaluate the effects of inorganic versus amino acid complexed sources of trace minerals on feline skin and haircoat characteristics as well as hair growth. A total of 40 cats (age 5 – 12 years; 22 female, 18 male) were used in this 105-d (15-d acclimation; 90-d test period) trial at Summit Ridge Farms (Susquehanna, PA) from January to April 2022. All cats were fed a basal diet that contained sulfate sources of trace minerals formulated to meet AAFCO (2021) recommendations for 15 d before being randomly assigned (blocked by haircoat color, age, sex, and weight) to 1 of 2 treatments. Dietary treatments included sulfate sources (CON; n = 20) and amino acid complexed (Zinpro ProPath, Zinpro Corp. Eden Prairie, MN) sources (ZPM; n = 20) of supplemental trace minerals. Both treatments were formulated to provide equal amounts of supplemental trace minerals (DM basis), differing only in source (100 ppm Zn, 15 ppm Mn, 12 ppm Cu, 80 ppm Fe). On d 15, a side patch was shaved just below the back (3” x 4”) to evaluate hair growth on d 60 and 105 (average of 3 measurements). Additionally, visual haircoat evaluations and shed hair amount were evaluated at d 60 and 105. All research personnel were blinded to treatments. Statistical analyses were completed using GLIMMIX procedure of SAS 9.4 with d 15 as a covariate and cat as the experimental unit. Trace mineral source did not affect body condition score at either time point. There was no treatment or treatment x day interaction for hair length. A trend (p = 0.13) for a 3-way interaction between treatment, sex, and day was detected due to male cats having longer hair at d 105. Shed hair was evaluated by brushing (20 strokes) and weighing collected hair. No overall treatment effect was detected for shed hair; although, a treatment x day interaction (P = 0.02) for shed hair was observed. At d 60, ZPM cats had 23 mg less shed hair compared with CON cats (P = 0.08). Haircoat scores for shine, scale, and overall quality were assessed by a veterinarian. There were no treatment or treatment x day interactions for shine or overall scores. A treatment x day interaction was detected (P = 0.02) for scale (dander). At d 60, ZPM cats had a reduced average scale score compared with CON cats (0.66 vs 1.05, respectively; P = 0.03). Overall, our data suggests trace mineral source may influence shed hair amount and dander production in cats. Further research to evaluate the influence of season and sex is warranted.

Altered fecal microbiota, IgA, and fermentative end-products in adult dogs fed prebiotics and a nonviable Lactobacillus acidophilus.

A study investigating the use of a nonviable Lactobacillus acidophilus (NVL: Culbac; TransAgra, Storm Lake, IA) and a mixed prebiotic (MP) blend (beet pulp, fructooligosaccharide (FOS), mannanoligosaccharide (MOS), inulin, and kelp) was done to evaluate changes in fecal microbiota, fermentative end products, and gut immune health in healthy female and male adult Beagle dogs (n = 24; 5.74 ± 2.18 yr; 9.30 ± 1.32 kg). The study protocol was first approved by the facility's Institutional Animal Care and Use Committee (Summit Ridge Farms; Susquehanna, PA) and followed throughout. Each of four test diets (control, NVL, MP, and MP + NVL [formulated to crude protein 25%, crude fat 14%, crude fiber 10% as-fed]) was fed once daily to maintain body weight for 21 d in a randomized-crossover design (four treatment periods and four washout periods). Fecal samples were collected on days 0 and 21 only for immunoglobulin A (IgA) and microbiota evaluation (16S rRNA V4 region and qPCR for Escherichia coli and Bifidobacterium), and fecal fermentative end-products and fecal pH were assessed only on day 21. Over the test periods, apparent total tract nutrient digestibility and stool quality were assessed. Data were analyzed by ANOVA (SAS v9.4, Cary, NC) or Kruskal-Wallis for between-diet effects, and paired t-test or Wilcoxon for time effects. Statistical significance was set at P ≤ 0.05. Apparent total tract nutrient digestibility revealed feeding MP-containing diets resulted in lower (P < 0.05) crude protein and fat digestibility vs. control and NVL diets. When dogs were fed MP, they had lower (P < 0.05) fecal pH compared with control and NVL diets, whereas fecal pH was lower in (P < 0.05) MP + NVL- vs. NVL-fed dogs. Fecal E. coli was (P < 0.05) lower at day 21 vs. day 0 when dogs were fed MP. Fecal Fusobacterium spp. was lower (P < 0.05) in both MP diets vs. control. Fecal Lactobacillus spp. increased (P < 0.05) from baseline with MP. Both diets with MP elicited greater (P < 0.05) fecal acetate and propionate concentration vs. control diet. At day 21, fecal IgA was greater (P < 0.05) in MP and MP + NVL compared with NVL diet. Only when dogs were fed MP did they have increased (P < 0.05) fecal IgA from day 21 vs. day 0. The MP + NVL diet decreased (P < 0.05) fecal isovalerate, isobutyrate, phenol, and indole vs. control. Overall, the MP elicited the most changes on microbiota, fermentative end-products, and IgA. Further investigation into NVL's gut health benefits is warranted.

Resurvey of vascular plants and soil arthropods on the summit of Mount Corazón (Andes of Ecuador) after 140 years

ABSTRACT Opportunities to track environmental changes over more than a century are rare in tropical mountains. Edward Whymper’s survey of flora and fauna on the summit of Mt. Corazón (Ecuador, 4788 m a.s.l.) in 1880 provides a unique opportunity to compare historical observations with the current composition of plant and insect communities on a tropical alpine mountain top. We studied Whymper’s archives and historic specimens in London and Paris, and performed a resurvey of vascular plants and ground beetles (Coleoptera Carabidae) in January 2020. Currently, a large part of the summit area of Corazón is heavily damaged by trampling and stone removal due to mountain tourism, and no vascular plants are present in the deteriorated area on the top of the ridge. However, more species were collected in 2020 than in 1880: 22 of vascular plants vs. 7, and 4 of ground beetles vs. 1. Upslope shifts over 140 years may partly explain this increase in species richness, although the low numbers of Whymper’s sampling may also be due to less skilled collectors and to the presence of permanent snow beds on the summit. The current faunistic and floristic data presented in this contribution can be used as a baseline for future resurveys of Corazón, in order to monitor changes in the species distribution and community composition of its summit area. Owing to the very small area of its superpáramo and to the soil deterioration by trampling along the summit ridge, Corazón is especially exposed to the effects of climate change and to the risk of extirpation of endemic cold-adapted specialists.

The 1845–46 and 1766–68 eruptions at Hekla volcano: new lava volume estimates, historical accounts and emplacement dynamics

We use new remote sensing data, historical reports, petrology and estimates of viscosity based on geochemical data to illuminate the lava emplacement flow-lines and vent structure changes of the summit ridge of Hekla during the large eruptions of 1845–46 and 1766–68. Based on the planimetric method we estimate the bulk volumes of these eruptions close to 0.4 km³ and 0.7 km³, respectively. However, comparison with volume estimates from the well-recorded 1947–48 eruption, indicates that the planimetric method appears to underestimate the lava bulk volumes by 40–60\%. Hence, the true bulk volumes are more likely 0.5–0.6 km³ and 1.0–1.2 km³, respectively. Estimated melt viscosity averages for the 1766–68 eruption amount to 2.5×10² Pa s (pre-eruptive) and 2.5×10³ Pa s (degassed), and for the 1845–46 eruption 2.2×10² Pa s (pre-eruptive) and 1.9×10³ Pa s (degassed). Pre-eruptive magmas are about one order of magnitude more fluid than degassed magmas. In the 1845–46 and 1947–48 eruptions, SiO$_2$ decreased from 58–57 to 55–54 wt\% agreeing with a conventional model that Hekla erupts from a large, layered magma chamber with the most evolved (silicarich) magmas at the top. In contrast, the lava-flows from 1766–68 reveal a more complicated SiO$_2$ trend. The lava fields emplaced in 1766 to the south have SiO$_2$ values 54.9–56.5\%, while the Hringlandahraun lava-flow that erupted from younger vents on the NE end of the Hekla ridge in March 1767 has higher SiO2 of 57.8\%. This shows that the layered magma chamber model is not suitable for all lava-flows emplaced during Hekla eruptions.

Conflicting science requirements impact on rare moss conservation measures

AbstractThe Antarctic Treaty recognizes the outstanding scientific values of the Antarctic environment through the designation of Antarctic Specially Protected Areas (ASPAs) that have rigorous management plans specific to each site. Deception Island has the largest concentration of rare bryophyte species and communities in Antarctica, while also offering substantial opportunities for research in a range of scientific disciplines due to its volcanic nature. As a result, conflicts between research interests and conservation goals may arise. On the summit ridge of Caliente Hill severe trampling damage to the moss assemblages growing in association with localized geothermal activity was observed. The range of species affected included the entire known population of Schistidium deceptionense, an endemic moss known only from this site, as well as other very rare Antarctic mosses (Ditrichum ditrichoideum, Bryum orbiculatifolium, Bucklandiella subcrispipila, Pohlia wahlenbergii and Dicranella hookeri). A photomapping study was undertaken to characterize further the status of the site and monitor changes within it. Increased awareness, co-ordination of activities and a spatial zoning within the site could help mitigate damage from permitted activities. Nevertheless, prioritization of longer term conservation goals over short-term research interests may ultimately be necessary where local human impact cannot be managed by other means.

The Gondou hydrothermal field in the Ryukyu Arc: A huge hydrothermal system on the flank of a caldera volcano

AbstractHigh‐resolution geophysical mapping was conducted from an autonomous underwater vehicle on the flank of Daisan‐Kume Knoll in the Ryukyu Arc, southwest of Japan. 1 m resolution bathymetry identified 264 spires, 173 large mounds and 268 small mounds within a depression that is up to 1600 m wide and up to 60 m deep, at water depths between 1330 and 1470 m. Hydrothermal venting is strongly inferred from the observation of plumes in sidescan sonar imagery and positive temperature anomalies over the spires and mounds. This field, named the Gondou Field, has a giant mound G1 with a diameter of 280 m and a height of 80 m. Mound G1 has distinctive summit ridges composed of multiple spires where acoustic plumes with temperature anomalies up to 1.12°C are observed, indicative of high‐temperature venting. Other than mound G1, a number of active large mounds more than 30 m wide and spires over 10–22 m tall are common and they concentrate in the central and southern areas of the field, suggesting that these areas are the center of present hydrothermal activity. Acoustic plumes imaged by side‐scan sonar at the Gondou Field are different in character from bubble plumes imaged in other hydrothermal fields in the Ryukyu Arc. The plumes are diffused and deflected as they rise through the water column and have a shape consistent with black smokers.

Reconstruction of the 2014 eruption sequence of Ontake Volcano from recorded images and interviews

A phreatic eruption at Mount Ontake (3067 m) on September 27, 2014, led to 64 casualties, including missing people. In this paper, we clarify the eruption sequence of the 2014 eruption from recorded images (photographs and videos obtained by climbers) and interviews with mountain guides and workers in mountain huts. The onset of eruption was sudden, without any clear precursory surface phenomena (such as ground rumbling or strong smell of sulfide). Our data indicate that the eruption sequence can be divided into three phases. Phase 1: The eruption started with dry pyroclastic density currents (PDCs) caused by ash column collapse. The PDCs flowed down 2.5 km SW and 2 km NW from the craters. In addition, PDCs moved horizontally by approximately 1.5 km toward N and E beyond summit ridges. The temperature of PDCs at the summit area partially exceeded 100 °C, and an analysis of interview results suggested that the temperature of PDCs was mostly in the range of 30–100 °C. At the summit area, there were violent falling ballistic rocks. Phase 2: When the outflow of PDCs stopped, the altitude of the eruption column increased; tephra with muddy rain started to fall; and ambient air temperature decreased. Falling ballistic rocks were almost absent during this phase. Phase 3: Finally, muddy hot water flowed out from the craters. These models reconstructed from observations are consistent with the phreatic eruption models and typical eruption sequences recorded at similar volcanoes.

Ligand Noninnocence in Coinage Metal Corroles: A Silver Knife-Edge

Invited for the cover of this issue are Abhik Ghosh and his collaborators at UiT (The Arctic University of Norway, Tromsø) and in the United States. The image depicts a silver corrole complex poised on the summit ridge of Mount Sir Alexander, a peak of the Canadian Rockies (image courtesy of Chris Goulet), symbolizing the balance between innocent and noninnocent ligands. Read the full text of the article at 10.1002/chem.201502150.

Ground-layer turbulence evaluation project at Subaru Telescope

A candidate of the next-generation adaptive optics (AO) system at Subaru Telescope is a ground-layer AO (GLAO) using an adaptive secondary mirror. The performance of GLAO depends on the turbulence profile because only ground-layer turbulence is corrected. At Mouna Kea, the profile data have been obtained at the summit ridge site and TMT site. However, the height difference of the Subaru site from these sites is about 100 m, close to the scale height of the ground-layer turbulence. There is a possibility that the topographical difference affects the ground-layer turbulence property, and then the performance of GLAO. In this paper, the activity to evaluate the ground-layer turbulence at the Subaru site is introduced.

Using a Snow Drift Model to Simulate Eolian Drift and Snowfall on the Summit of Mauna Kea, Hawaii

The goal of this research is to help develop a better understanding of the micro-meteorology of the Mauna Kea summit area and its relationship to the distribution and population health of the Wēkiu bug (Nysius wekiuicola). SnowModel, a spatially distributed snow-evolution model, is used to construct snowfall and summit eolian debris (known as bug fall throughout this study) accumulation maps across the summit. Eight weather stations associated with astronomical observatories on the summit ridges and four Davis weather stations located in various cinder cones (pu‘u in Hawaiian), provide the meteorological observations needed as input to run SnowModel. Snow depth observations taken after a passing cold front in January 2011 are used to help validate the model accumulation predictions prior to the climatological study. Observations from summit weather stations over a three-year period (2008, 2009, and 2010) are used as input for the modeled summit accumulations of snowfall and bug fall presented in this study. For the snowfall maps, only weather data from days during which snow fell are included. For the bug-fall estimates, all days where valid weather data are available are included in the model output. Since there are no comprehensive data available on the distribution of bug fall, the bug-fall maps only provide a climatological pattern, without reference to the magnitude of the bug fall. The greatest modeled snow accumulations are found on Pu‘u Wēkiu and Pu‘u Haukea. Similar results are found in the climatological bug-fall accumulation pattern. Prevailing wind direction is most critical for the distribution of snowfall and bug fall, with maximum accumulations occurring on the lee side of ridges and crests. Favorable Wēkiu bug trapping sites in which bugs were found historically are spatially well collocated with snowfall and bug-fall accumulations, suggesting that the results of this study will be of interest to entomologists in locating Wēkiu bug populations.

10Be and 26Al exposure‐age dating of bedrock surfaces on the Aran ridge, Wales: evidence for a thick Welsh Ice Cap at the Last Glacial Maximum

AbstractThis paper presents results of the analysis of paired cosmogenic isotopes (10Be and 26Al) from eight quartz‐rich samples collected from ice‐moulded bedrock on the Aran ridge, the highest land in the British Isles south of Snowdon. On the Aran ridge, comprising the summits of Aran Fawddwy (905 m a.s.l.) and Aran Benllyn (885 m a.s.l.), 26Al and 10Be ages indicate complete ice coverage and glacial erosion at the global Last Glacial Maximum (LGM). Six samples from the summit ridge above 750–800 m a.s.l. yielded paired 10Be and 26Al ages ranging from 17.2 to 34.4 ka, respectively. Four of these samples are very close in age (10Be ages of 17.5 ± 0.6, 17.5 ± 0.7, 19.7 ± 0.8 and 20.0 ± 0.7 ka) and are interpreted as representing the exposure age of the summit ridge. Two other summit samples are much older (10Be ages of 27.5 ± 1.0 and 33.9 ± 1.2 ka) and these results may indicate nuclide inheritance. The 26Al/10Be ratios for all samples are indistinguishable within one‐sigma uncertainty from the production rate ratio line, indicating that there is no evidence for a complex exposure history. These results indicate that the last Welsh Ice Cap was thick enough to completely cover the Aran ridge and achieve glacial erosion at the LGM. However, between c. 20 and 17 ka ridge summits were exposed as nunataks at a time when glacial erosion at lower elevations (below 750–800 m a.s.l.) was achieved by large outlet glaciers in the valleys surrounding the mountains. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Evidence that three seamounts off southern California were ancient islands

Many seamounts world-wide exhibit features that suggest they were once islands. Rodriguez and San Juan Seamounts and Northeast Bank, within 250 km of the continental margin of the western US, were explored with the ROV Tiburon and found to have guyot morphology, beach deposits and erosional features, degassed volcanic lavas and pyroclasts, and cooling and alteration patterns unusual for submarine erupted lavas. These features are evaluated as evidence that the volcanoes stood above sea level. The summit of Rodriguez Seamount is a smooth, gently domed platform. Rough hills stand above the platform and consist of dense, degassed ‘a‘a flows erupted subaerially. Bedded sandstones and rounded cobbles interpreted to be beach deposits occur near the top of a major break-in-slope at about 700 m depth. The summit of Northeast Bank is also a smooth, gently domed platform. Beach deposits were observed just below the pronounced break-in slope at about 500 m. The summit of San Juan Seamount is a northeast-southwest trending series of rough ridges rather than a dome. However, subaerially exposed ‘a‘a-like lava flows were found above 700 m. Oxidized olivine, degassed volcanic glass, and secondary phosphatization of the lavas are found both shallower and deeper than the breaks-in-slope, and their presence may not be robust indicators of subaerial exposure. Rodriguez stood at least 70 m above sea level and formed a small island 6.8 km 2 in area prior to subsiding at least 700 m. Northeast Bank was a large island perhaps 200 m above sea level and 90 km 2 in area. The summit ridge of San Juan emerged as a line of eight small islands with a total area of about 2.8 km 2, and the tallest island rose at least 140 m above sea level. The subsidence of Northeast Bank within the California borderland, Rodriguez Seamount on the continental slope, and San Juan Seamount on the adjacent ocean crust occurred since they formed 7 to 11 million years ago. The minimum subsidence is consistent with cooling and contraction of the underlying lithosphere.

Identity and emplacement of domical structures in the western Arcadia Planitia, Mars

Morphologic, morphometric, and thermophysical aspects of domical structures in a restricted part of the Mars northern plains were characterized using Mars Odyssey and Mars Global Surveyor data. The majority of domical structures consist of relatively high thermal inertia, subcircular to irregularly shaped “core' bodies surrounded by adjacent, relatively low‐albedo, low thermal inertia “annuli,” and dispersed aureoles of apparently disaggregated material. Core profiles vary considerably from low to high aspect ratios. Elongate “arms” of material extend from the central, summit regions in some of the structures. Core features include apparent blocky surface texture, summit fissures and pits, apparent summit and flank ruptures suggestive of “eruption” of material, and concentric and straight summit ridges. Core heights range from ∼30 to 400 m, mean = 160 m, diameters range from ∼620 to 3090 m, mean = 1550 m, aspect ratios range from 0.02 to 0.36, mean = 0.11, and volumes range from ∼0.1 to ∼1.8 km3. An additional morphologic type consists of subcircular, domical mounds that are apparently covered by plains materials. We propose that the majority of the structures are partially extrusive cryptodomes and lava domes, whereas the mounds are entirely intrusive cryptodomes.

Effects of human disturbance and cryoturbation on soil iron and organic matter distributions and on carbon storage at high elevations in the Cairngorm Mountains, Scotland

Soil profiles were sampled at 43 sites on granitic parent material at altitudes ranging from 970 to 1300 m in the Cairngorm Mountains, Scotland. Many soils under undisturbed vegetation showed evidence of iron and organic matter translocation with distinctive Bh or Bs horizons. Approximately 50% of the sites sampled had no or partial vegetation cover, due either to human activity (trampling) or active geomorphic processes such as cryoturbation on patterned ground. Exposed cols and summit ridges were most heavily affected by trampling with extensive areas of path development and some erosion. Trampling was principally associated with loss of the upper soil horizons and cryoturbation processes with disturbance of horizon development. Median total organic matter at the vegetated sites ranged from 4.8 to 22.0 kg m −2 with a median of 9.5 kg m −2. There was significantly less total organic matter at the unvegetated sites with median of 4.6 kg m −2 and range from 1.5 to 11.9 kg m −2. There was little difference in total organic matter between sites where vegetation disturbance was due to human trampling or to cryoturbation.

USING GIS IN THE PROBABILISTIC ASSESSMENT OF EARTHQUAKE TRIGGERED LANDSLIDE HAZARDS

Summit Ridge, located in the North Santa Cruz Mountains, California, was heavily affected by landsliding during the 1989 Loma Prieta earthquake (Mw=7.0). Widespread shallow failures, along with 17 deep-seated landslides, caused extensive damage. In order to study possible methods of assessing landslide hazard a geographical information system (GIS) was utilised. Geological, geotechnical, geomorphological and seismological data were used in a deterministic analysis using two standard earthquake slope stability models (pseudo-static and Newmark displacement). The models were used to assess the landslide potential that existed during the Loma Prieta event. It was found that, of these two models, the Newmark displacement model proved most successful at predicting the location of shallow unstable slopes. However, because both models are deterministic in nature they did not take into account any of the error and uncertainty in the input parameters. Therefore, a probabilistic Newmark displacement method of analysis was developed. This was achieved by incorporating the principles behind a recently developed probabilistic technique which utilises the pseudo-static slope stability model. The method calculates the probability that a slope will exceed a certain critical value of Newmark displacement and thus fail. The use of such an analysis resulted in a more realistic distribution of hazard when compared with the distribution of actual landslides triggered by the 1989 earthquake. Subsequent to this, the probabilistic method was used to undertake a landslide hazard assessment for Summit Ridge given a postulated earthquake located on the Northern East Bay segment of the Hayward fault.

Coseismic deformation of the Wrights tunnel during the 1906 San Francisco earthquake: A key to understanding 1906 fault slip and 1989 surface ruptures in the southern Santa Cruz Mountains, California

The Wrights tunnel is an abandoned railroad tunnel that crosses the San Andreas fault in the southern Santa Cruz Mountains in the vicinity of the 1989 Loma Prieta earthquake. The tunnel was damaged and deformed during the 1906 San Francisco earthquake and a plot showing postearthquake measurements made in the tunnel is given by Lawson [1908]. The amount of offset shown on this plot (1.5 m) has been used in several studies as being representative of the amount of fault offset along this segment of the San Andreas fault in 1906. Our historical research shows that different observers reported different amounts of fault offset in the tunnel and that the 1.5 m given on the plot is not a surveyed measurement. In addition, the plot of the tunnel has been interpreted in several previous studies as evidence of a broad (1.5 km) zone of faulting beneath Summit Ridge. Our analysis shows that this plot need not indicate a broad zone of deformation. Our historical research and modeling of the tunnel measurements indicate that faulting was confined to a zone less than 400 m wide and that 60–85% of the coseismic slip occurred across a single fault plane. There is no evidence for offset across a second shear zone beneath Summit Ridge in 1906. This implies that surface fractures reported on Summit Ridge in 1906 were not associated with significant deformation of the tunnel, implying that they were shallow, surficial features. By analogy, the very similar fractures that occurred on Summit Ridge in 1989 were also probably the result of shallow gravitational, rather than deep‐seated tectonic, processes. Our modeling also indicates that total coseismic, near‐surface slip across the San Andreas fault zone in the Wrights tunnel in 1906 was at least 1.7–1.8 m.

Formation of left‐lateral fractures within the Summit Ridge Shear Zone, 1989 Loma Prieta, California, Earthquake

The 1989 Loma Prieta, California, earthquake is characterized by the lack of major, throughgoing, coseismic, right‐lateral faulting along strands of the San Andreas fault zone in the epicentral area. Instead, throughout the Summit Ridge area there are zones of tension cracks and left‐lateral fracture zones oriented about N45°W, that is, roughly parallel to the San Andreas fault in this area. The left‐lateral fractures zones are enigmatic because their left‐lateral slip is opposite to the right‐lateral sense of the relative motion between the Pacific and North American plates. We suggest that the enigmatic fractures can be understood if we assume that coseismic deformation was by right‐lateral shear across a broad zone, about 0.5 km wide and 4 km long, beneath Summit Ridge. The shear zone has an orientation of about N70° W and is oblique to the San Andreas fault zone, which has a trend of N45° to 50°W, so that right‐lateral shearing, along with some dilation, can account for the orientation of the fracture zones. Using an analog, kinematic model of the Summit Ridge shear zone and the observable geometric parameters (a shear zone about 0.5 km wide, an acute angle of 25° between the tension cracks and the shear‐zone walls, left‐lateral slip of 5 cm, and spacing of about 100 m in the tension cracks) we estimate that the amount of right‐lateral shift across the Summit Ridge shear zone was on the order of 1.4 m. This is comparable to the amount of slip for coseismic faulting at depth, 1.9 to 2.4 m, as computed by several investigators. Thus contrary to most previous reports on the Loma Prieta earthquake, which assert that coseismic, right‐lateral ground rupture was restricted to considerable (greater than 4 km) depths in the epicentral area, we find that nearly all the right‐lateral offset is represented at the ground surface by the Summit Ridge shear zone.

ECOTYPIC DIVERGENCE IN ALPINE POLEMONIUM VISCOSUM: GENETIC STRUCTURE, QUANTITATIVE VARIATION, AND LOCAL ADAPTATION.

Polemonium viscosum has a continuous distribution from 3,500 m in the krummholz to 4,025 m on the summit ridges of Pennsylvania Mountain, Colorado. Seeds produced by plants at opposite ends of this cline, 1.5 km apart, differed significantly at allozyme loci in two consecutive breeding seasons. Mean multilocus Fst values for both years (0.015 and 0.069) were significantly different from zero, indicating restricted gene exchange between subpopulations. Average allele frequencies at two individual loci also differed significantly between families comprising krummholz and summit subpopulations. Progeny of plants growing on the summit had higher leaf production rates, more densely packed leaflets, and lower resistance to aphids than progeny of plants growing in the krummholz site, when tested under greenhouse conditions. These differences probably reflect the restricted opportunities for growth and severe exposure at high elevations, and the increased risk from herbivores near timberline. The two subpopulations did not differ in leaf length (stature), leaf width, or pubescence. Reciprocal transplanting of seedlings between krummholz and summit sites confirmed that the differences were adaptive, since progeny from each subpopulation performed significantly better in their parent's habitat. Coordinated studies of genetic structure, quantitative variation, and local adaptation across the elevational range of P. viscosum provide a comprehensive view of ecotypic divergence in this widespread alpine plant.

Courtship and use of mating areas by grizzly bears in the Front Ranges of Banff National Park, Alberta

In five of six observations of courting grizzly (brown) bears (Ursus arctos), pairs were isolated on a summit or upper-elevation ridge where the male repeatedly blocked the female's descent. These observations substantiate an earlier single observation of this mating behaviour. Similar isolation of mating grizzly bears on summits or ridges has not been reported elsewhere in North America. The habitat of the mating areas is described. The areas were not grizzly bear feeding habitat. Food intake evidently was reduced during the period of isolation. These observations are interpreted as male sequestering of an oestrus female and female testing of male vigour.

Botanical features of northeastern Great Barrier Island, Hauraki Gulf, New Zealand

Abstract The main features of the vegetation and a vascular flora are given for an area of some 1,330 hectares in the north-eastern sector of Great Barrier Island. Only patches of original forest remain. The predominant vegetation is regenerating forest and scrub, with small areas of grassland along the coast and on the summit ridge. Vegetation succession and f10ristic composition have been extensively modified by pigs and goats. A small island free of these animals, adjacent to the study area, demonstrates the impact of pigs and goats on the vegetation of the main island. The recent accelerated erosion of the area is discussed. An annotated species list of vascular plants is presented. Of the 441 taxa recorded, 334 (76%) are native. Several taxa achieve the northern limit of their distribution in the study area, and the status of rare plants found is discussed.