Channel Islands National Park Research Articles

A tale of two islands: tectonic and orbital controls on marine terrace reoccupation, Channel Islands National Park, California, USA

AbstractIn areas of low uplift rate on the Pacific Coast of North America, reoccupation of emergent marine terraces by later high sea‐stands has been hypothesised to explain the existence of thermally anomalous fauna (mixtures of warm and cool species) of last interglacial age. If uplift rates have been low for much of the Quaternary, it follows that higher (older) terraces should also show evidence of reoccupation. Strontium isotope analyses of fossils from a high‐elevation marine terrace on Anacapa Island, California, yield ages ranging from ~2.4–2.3 Ma to ~1.4–1.5 Ma. These results indicate that terrace reoccupation and fossil mixing on Anacapa Island could have taken place over several interglacial periods in the early Pleistocene. Terrace reoccupation over this time period is likely a function of both a low uplift rate and the timing of orbital forcing of glacial–interglacial cycles. Climate change in the early Pleistocene was modulated by the 41 ka obliquity cycle, and glacial–interglacial cycles were much shorter than later in the Pleistocene. Nearby San Miguel Island also has evidence of terrace reoccupation, with Sr isotope ages of shells from several high‐elevation terraces ranging from ~1.21–1.25 Ma to ~0.43–0.50 Ma. However, the frequency of terrace reoccupation was lower than on Anacapa Island. The uplift rate of San Miguel Island is higher than that of Anacapa Island and terraces formed when glacial–interglacial cycles were longer. The frequency of marine terrace reoccupation is controlled by the rate of tectonic uplift and the timing of orbital forcing of sea level change during glacial–interglacial cycles.

Review: Restoring Nature: The Evolution of Channel Islands National Park, by Larry M. Dilsaver and Timothy J. Babalis

Review: <i>Restoring Nature: The Evolution of Channel Islands National Park</i>, by Larry M. Dilsaver and Timothy J. Babalis

Restoring Nature: The Evolution of Channel Islands National Park, By Lary M. Dilsaver and Timothy J. Babalis

Restoring Nature: The Evolution of Channel Islands National Park, By Lary M. Dilsaver and Timothy J. Babalis

Conservation Paleobiology and the Stewardship of U.S. National Park Service Paleontological Resources

Conservation biology, and the descendent discipline conservation paleobiology, are philosophically aligned with the mission of the National Park Service (NPS), including near time and deep time frameworks. As defined in the Organic Act of August 25, 1916, the purpose and mission of the NPS is “…to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations”. This conservation mandate is broadly inclusive of grizzly bears, redwood trees, and dinosaur bones equally, throughout the 424 officially designated parks, monuments, and other areas managed by the NPS. Although conservation paleobiology is reported by some to be a new and integrated field of study, there are remarkable similarities to traditional and old school perspectives which embraced natural history more holistically during the nineteenth and early twentieth centuries. Notably, the written contributions by Charles Darwin, Aldo Leopold, and Edward Abbey synthesize observations at the global and landscape scales, promoting conservation advocacy of the natural world, past and present. U.S. National Park Service areas preserve some of Planet Earth’s most globally significant natural resources, ecological systems, and biosphere reserves. Discoveries of fossil condors and mummified bats within caves of Grand Canyon National Park, the co-occurrence of human and megafaunal footprints preserved in Late Pleistocene strata at White Sands National Park, and pygmy mammoth remains on Channel Islands National Park, collectively demonstrate how valuable temporal and historical biological perspectives contribute to science, stewardship, and resources management in parks and beyond. The paleobiology community is cordially invited to join in the holistic study and conservation of the near time and deep time resources in the national parks.

Obstacles to removing non-native species from a national park

Throughout its history, the National Park Service has sought to eliminate or control non-native species within its units. The growing influence of science in natural resource management has made this mandate ever more imperative. Removal of invasive vegetation has proven extremely difficult and may never be complete in many parks. Efforts to eliminate domesticated animals and feral or wild invaders have met many obstacles as well. Channel Islands National Park has managed to get rid of sheep, cattle, pigs, burros, horses, deer, elk, rats, cats, rabbits, turkeys, Argentine ants, and European honey bees. In the process, park managers have had to work through or overcome eight types of impediments as well as virulent opposition. Lessons learned from these campaigns can inform other park managers facing the same types of problems.

A complex record of last interglacial sea-level history and paleozoogeography, Santa Rosa Island, Channel Islands National Park, California, USA

Studies of marine terraces and their fossils can yield important information about sea level history, tectonic uplift rates, and paleozoogeography, but some aspects of terrace history, particularly with regard to their fossil record, are not clearly understood. Marine terraces are well preserved on Santa Rosa Island, California, and the island is situated near a major marine faunal boundary. Two prominent low-elevation terraces record the ∼80 ka (marine isotope stage [MIS] 5a) and ∼120 ka (MIS 5e) high-sea stands, based on U-series dating of fossil corals and aminostratigraphic correlation to dated localities elsewhere in California and Baja California. Low uplift rates are implied by an interpretation of these ages, along with their elevations. The fossil assemblage from the ∼120 ka (2nd) terrace contains a number of northern, cool-water species, along with several southern, warm-water species, a classic example of what has been called a thermally anomalous fauna. Low uplift rates in the late Pleistocene, combined with glacial isostatic adjustment (GIA) processes, could have resulted in reoccupation of the ∼120 ka (MIS 5e), 2nd terrace during the ∼100 ka (MIS 5c) high-sea stand, explaining the mix of warm-water (∼120 ka?) and cool-water (∼100 ka?) fossils in the terrace deposits. In addition, however, sea surface temperature (SST) variability during MIS 5e may have been a contributing factor, given that Santa Rosa Island is bathed at times by the cold California Current with its upwelling and at other times is subject to El Niño warm waters, evident in the Holocene SST record. Study of an older, high-elevation marine terrace on the western part of Santa Rosa Island shows more obvious evidence of fossil mixing. Strontium isotope ages span a large range, from ∼2.3 Ma to ∼0.91 Ma. These analyses indicate an age range of ∼500 ka at one locality and ∼ 600 ka at another locality, interpreted to be due to terrace reoccupation and fossil reworking. Consideration of elevations and ages here also yield low, long-term uplift rates, which in part explains the potential for terrace reoccupation in the early Pleistocene. In addition, however, early Pleistocene glacial-interglacial cycles were of much shorter duration, linked to the ∼41 ka obliquity cycle of orbital forcing, a factor that would also enhance terrace reoccupation in regions of low uplift rate. It is likely that other Pacific Coast marine terrace localities of early Pleistocene age, in areas with low uplift rates, also have evidence of fossil mixing from these processes, an hypothesis that can be tested in future studies.

Roving Divers Surveying Fish in Fixed Areas Capture Similar Patterns in Biogeography but Different Estimates of Density When Compared With Belt Transects

Fish abundance and diversity are core measurements taken by many nearshore marine monitoring projects. The most common approaches for counting fish include belt transects and timed counts by roving divers, each with its own limitations. Here we evaluate a fish counting method developed by the Channel Islands National Park’s Kelp Forest Monitoring Program (KFMP), in which roving observers make fish counts that are standardized both by the time taken (30 min) and the area sampled (2000 m2). This method is potentially very useful because it combines an advantage of simple timed counts – the ability to rapidly sample a large area – with the potential to calculate area-specific density of fish, not just their relative abundance. However, the method has not been comprehensively evaluated and it is uncertain whether fish can effectively be counted in such a large target area within the allotted time. Fortunately, many sites surveyed with this method are also sampled with a more standard fish counting approach of belt transects, both by the KFMP and by the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO). Here we compare estimates of fish density obtained through the area-standardized roving diver method and belt transect methods. In paired samples we find substantial and species-specific differences in densities estimated by each method. Considering all fish taxa together we find that roving divers are likely under-sampling the target area. Despite considerable species-level variation, the different methods produce similar estimates of average diversity and find similar regional and temporal patterns in fish abundance, demonstrating that they can successfully be used in parallel even if the datasets cannot be easily combined. These analyses can guide the interpretation of roving diver data for basic research and management decisions.

Soundscapes indicate kelp forest condition

Soundscapes are promising indicators of marine habitat condition, yet this approach remains untested in many ecosystems, and soundscape-ecological relationships remain unclear. In this study, we analyzed soundscapes in kelp forest habitats off the coast of California, USA, in Channel Islands National Park. We investigated if (1) soundscape features correlated with ecological variables and (2) these features differed inside and outside of marine protected areas (MPAs). We recorded 1 min every 15 min at 5 sites from 12 May to 23 June 2018. Three sites were in MPAs with high kelp cover and low urchin density, while 2 were in adjacent, unprotected habitats with low kelp cover and high urchin density. To analyze the data, we calculated soundscape features using detection algorithms and acoustic indices, which we then correlated with annual ecological data from 2016 to 2018. We found that drivers of regime shifts in kelp forests, i.e. sea urchin density, kelp cover, and fish diversity, were significantly related to soundscape features. Sea urchin density was positively correlated and kelp cover negatively correlated with the rate of shrimp snaps. Fish species richness and abundance were positively correlated with the intensity and diel dynamics in the low-frequency bands that contained most fish vocalizations. This study demonstrates that marine soundscapes indicate the condition of kelp forests, which are vulnerable to destruction from urchin overgrazing. If marine soundscapes can reliably indicate the status of ecological drivers, then this approach could be a valuable complement to diver surveys in fully assessing marine ecosystem health.

Fluvial sedimentary history of Arlington Canyon, Channel Islands National Park, California

ABSTRACTArlington Canyon, in the northwest part of Santa Rosa Island, Channel Islands National Park, California, has been the setting for important scientific discoveries over the past half century, including the oldest human remains in North America, several vertebrate fossil sites, and purported evidence of a catastrophic extinction event at the end of the Pleistocene. The canyon is filled with alluvial sediments that date to between 16.4 and 1.1 ka (thousands of calibrated years before present), representing accumulation that occurred primarily in response to rising sea levels during the late Pleistocene and Holocene. The deposits are laterally discontinuous, exhibit a high degree of sedimentary complexity, and contain evidence of past climates and environments, including fossil bones, burned plant macrofossils, and invertebrate microfossils. Here, we show that it is critical to view the observations, data, and conclusions of scientific studies conducted in the canyon within this larger context so that localized facets of the spatially and temporally extensive alluvial deposits are not misinterpreted or misrepresented. By improving the baseline understanding of processes and drivers of sediment accumulation in Arlington Canyon, we hope to offer a solid foundation and better underpinning for future archeological, paleontological, and geochemical studies here and throughout the northern Channel Islands. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.

Black abalone (Haliotis cracherodii) population structure shifts through deep time: Management implications for southern California's northern Channel Islands.

For over 10,000 years, black abalone (Haliotis cracherodii) were an important resource in southern California, first for coastal Native Americans, then beginning in the nineteenth century, as one of the state's first commercial shellfisheries. By 1993, after years of heavy fishing, rising sea surface temperatures (SST), and the spread of withering syndrome (WS), black abalone populations declined dramatically, resulting in the closure of the Alta California fishery. After nearly 25 years of management and recovery efforts, black abalone are showing signs of ecological rebound along some Channel Island shorelines. These include the presence of juvenile abalone and increasing densities, largely from data collected by Channel Islands National Park (CINP) monitoring efforts that began in 1985.In an effort to apply deeper historical perspectives to modern fisheries management and restoration, we analyzed black abalone size data from San Miguel Island at prehistoric and historical archeological sites spanning the last 10,000 years and compared these populations to those described by CINP biologists between 1985 and 2013.We found a statistically significant relationship between SST and black abalone size distributions during the ancient record, along with dramatic shifts in population size structure toward larger individuals between the nineteenth century and modern periods. A pattern of larger mean black abalone sizes was identified during warm SSTs, when compared against intervals of cooler SSTs.Synthesis and applications. Our study provides a deep historical perspective of abalone population size distributions, patterns within these distributions through time, and parallels to modern abalone populations. Our results may help managers determine whether the current (and future) size and age structure of intertidal black abalone populations around the northern Channel Islands are “natural” and healthy, measured against the 10,000 year history of black abalone fishing in southern California.

Comparing the social values of ecosystem services in US and Australian marine protected areas

Spatially explicit models for conservation planning often rely on environmental and economic indicators to prioritize management decisions. Consideration of social values in relation to landscape metrics is less common, especially across different biophysical contexts. In this paper, we compare social values mapped by outdoor recreationists who visited Santa Cruz Island within Channel Islands National Park, USA, and Hinchinbrook Island National Park, Australia using a Social Values for Ecosystem Services mapping tool that interfaced with Maximum Entropy modeling. Specifically, we determine the relative importance of 12 social values and evaluate how the relationship between three highly rated social values (Aesthetic, Biological Diversity, and Recreation) and four biophysical metrics (distance to the coast, distance to management infrastructure, slope, and elevation) differed between two marine protected areas. Our results provide insight into the spatial dynamics of social-ecological data to identify high and low priority locations in protected areas as well as enable resource management agencies to make more informed decisions about how best to engage with stakeholders. This research also supports public involvement in policy-making about land and seascapes in the USA and Australia.

Little Islands Recording Global Events: Late Quaternary Sea Level History and Paleozoogeography of Santa Barbara and Anacapa Islands, Channel Islands National Park, California

Marine terraces are common on the Pacific Coast of North America and record interglacial high-sea stands superimposed on either stable or tectonically rising crustal blocks. Despite many years of study of these landforms in southern California, little work on terraces has been conducted on the two smallest of the California Channel Islands, Santa Barbara Island (SBI) and Anacapa Island (ANA). Presented here are new field and laboratory data on the ages, paleontology, and sea level history of marine terraces of these two islands. On both islands, the lowest marine terraces have shoreline angle elevations of ∼11 m above sea level. Amino acid geochronology shows that terrace deposits on both islands host fossils of two ages, one group dating to the ∼120-ka high-sea stand and the other group likely dating to the ∼100-ka high-sea stand. A mix of fossil ages is consistent with the paleontology as well, with SBI in particular showing a faunal assemblage that includes both extralimital southern and southward-ranging species (inferred to be from the ∼120-ka high-sea stand) and extralimital northern and northward-ranging species (inferred to be from the ∼100-ka high-sea stand). Fossil mixing from these two high-sea stands supports the hypothesis that glacial isostatic adjustment (GIA) processes have left a strong imprint on the geologic record of sea level history in southern California. Nevertheless, the elevations of these terraces and that of a low terrace on Santa Cruz Island indicate that modeled GIA estimates of paleo-sea level for the peak of the last interglacial period at ∼120 ka could be too high. Future development of models of GIA effects on the Pacific Coast of North America will need to consider geologic records, such as those from SBI and ANA, in refining reconstructions of sea level history.

Quantifying Surface Water on Santa Rosa Island, California, Following a Major Five-Year Drought

Although it is critical for survival of plants and animals, and for understanding prehistory of early humans, little work has been done on the stream hydrology of the California Channel Islands. In September 2014, August 2016, and October 2017, during the driest period of the year, park staff and volunteers mapped surface water on Santa Rosa Island, Channel Islands National Park, by walking drainages (2nd order and higher) and recording the location of surface water using consumer-grade Global Positioning System (GPS) units. In 2014, mappers hiked 293 km (182 miles) of stream channel in 19 major drainage basins and 7 lesser drainage basins. The hiking teams recorded 759 water features (pools and springs) and 67 km (42 miles) of surface water. The 2016 repeat mapping in Verde, Trancion, Arlington, and San Augustin canyons, the 4 wettest drainages in 2014, showed that surface water declined by 10.1%, 21.1%, and 34.2% for the first 3 canyons, respectively; surface water in San Augustin increased by 1.3% between 2014 and 2016. Repeat mapping in 2017 of Verde, Trancion, Arlington, San Augustin, and Water canyons showed an increase from 28.3% to 90.0% in surface water following an above-average rainfall year in 2016–2017. Results have important implications for plant and animal life that depend on water on Santa Rosa Island.

Vegetation Trends in a Restored Coastal Wetland at Prisoners Harbor, Santa Cruz Island, Channel Islands National Park

Prisoners Harbor on Santa Cruz Island, California, formerly supported a 5-ha wetland and riparian system, the largest on the California Channel Islands. During the late 1800s ranchers filled in about half of the wetland area in order to support ranching activities. They also rerouted the stream channel to the canyon edge and built an earthen berm along its west bank, which disconnected the stream from its floodplain. The National Park Service developed a wetland and riparian restoration design for Prisoners Harbor based on topographic and hydrologic analyses and on vegetation community depth-to-water-table relationships developed from neighboring reference wetlands. In 2011 Channel Islands National Park and The Nature Conservancy restored 1.25 ha of coastal wetlands by removing artificial fill and the earthen berm. Postproject vegetation monitoring during 2012 to 2016 showed increased abundance of 3 of the 8 herbaceous planted wetland species and declines in target invasive species. Severe drought conditions during this window likely influenced vegetation abundance. Postrestoration hydrologic monitoring showed that the restored marsh met the federal wetland hydrology standard only twice: once in late 2011 before the drought began and then again in January–September 2017. An exceptionally large swell and high tide during winter 2015/16 resulted in saltwater flooding of the site; salinity returned to more typical values only slowly after this event. Expansion of wetland species, even during a historic drought and atypical seawater intrusion, suggests that this evidence-based approach to restoration design will result in functional coastal wetland habitat as more typical precipitation levels return. However, we emphasize the need for aggressive control of nonnative plants until native plant cover is well established.

The Influence of Slope on Vegetation Recovery Following Nonnative Grazer Removal on Santa Rosa Island, California

Ecosystem restoration efforts have been ongoing on the Channel Islands of California since the 1980s. Although these island ecosystems evolved without ungulate grazers, large nonnative grazers, including sheep, cattle, feral pigs, deer, and elk, were present on the islands for over 160 years. Intensive grazing led to reductions in the extent of woody vegetation, increases in the area of grassland and bare ground, and widespread landsliding and gully erosion. This study focuses on Santa Rosa Island, the second largest (215.3 km2) island in Channel Islands National Park. After the park was created in 1980, the National Park Service progressively removed nonnative grazers to facilitate the restoration of native vegetation and the wildlife communities they support. We constructed a time series (1989 to 2015) of Landsat TM5 and Landsat 7 ETM+ images to evaluate large-scale and long-term vegetation change in response to grazer removal on Santa Rosa Island. We also evaluated the influence of slope percent, which can be an indicator of past grazing accessibility, on ecosystem recovery. Results indicate that removing nonnative grazers led to passive restoration of 42.1 km2 of scrub, chaparral, and woodland vegetation. In contrast, the area of grassland vegetation decreased by 31.2 km2 and bare ground decreased by 12.0 km2. The extent of scrub and woodland vegetation recovery was greater on gentle and moderate slopes compared to steep slopes, indicating that terrain does influence passive restoration. Despite changes in vegetation cover, 5.4 km2 has remained bare. Much of the bare ground is on ridgelines that were denuded down to the bedrock or regolith. Active restoration will be necessary on bare ridgelines, such as erosion control, fog capture, and oak woodland reforestation.

Marine Debris Trends: 30 Years of Change on Ventura County and Channel Island Beaches

The persistence of plastics in marine ecosystems and the physical hazards marine debris pose to wildlife have become issues of global concern. The Santa Barbara Channel is home to a number of important marine and coastal ecosystems, including the 5 islands of Channel Islands National Park, and has a variety of factors that influence marine debris accumulation. We examined the spatial variation of marine debris density and composition across the Santa Barbara Channel by quantifying marine debris on beaches of Santa Rosa and Santa Cruz Islands and the Ventura County mainland. Debris from surveyed beaches was cataloged, weighed, and measured to compare differences in island and mainland marine debris abundance, density, and composition. Derelict fishing gear accounted for a higher proportion of marine debris on island beaches compared to mainland beaches, and marine debris items on island beaches were significantly heavier compared to debris items on mainland beaches. The majority of debris on mainland beaches comprised smaller plastic fragments and single-use plastic items, and debris accumulation rates varied by season and location. Microplastics (plastic fibers and particles 25 mm) that were collected during marine debris cleanups. We compared our data from 2015 and 2016 with historical surveys performed from 1989 to 1994 to examine the temporal variation of marine debris on Santa Rosa Island. We found that there has been a significant increase in the amount of derelict fishing gear found on Santa Rosa Island over the past 27 years, which mirrors expansion of the California spiny lobster (Panulirus interruptus) fishery. This study highlights the importance of marine debris monitoring, as local changes in policy, fisheries, and consumer culture are reflected in accumulations of marine debris found on the California mainland and the uninhabited Channel Islands. Monitoring marine debris can provide insight into anthropogenic impacts and is a useful mechanism in monitoring the health of coastal and marine ecosystems.

Monitoring changes of NDVI in protected areas of southern California

California’s Mediterranean ecosystem has been identified as one of the Earth’s biodiversity hotspots. The high degree of rapid urbanization along the southern California coastline has resulted in the loss of significant natural areas over the last century and protected areas that do exist may be further threatened by climate change, drought, and fire. We use Moderate Resolution Imaging Spectroradiometer (MODIS) sensor at a 250 m pixel resolution and the Normalized Difference Vegetation Index (NDVI) to monitor temporal/spatial patterns from 2000 to 2016 within Santa Monica Mountains National Recreation Area and Channel Islands National Park. We test the hypothesis that there should be no significant long-term change in protected areas since 2000 and compare impacts of seasonality, drought, and fire. The Santa Monica Mountains National Recreation Area has experienced a long-term decline in vegetation greenness, vegetation types, and is the most significantly impacted with short-term declines during the summer with or without the impacts of fire. Change detection maps show areas of significant decline in NDVI in the Santa Monica Mountains National Recreation Area especially during the summer. The Channel Islands have relatively stable NDVI possibly due to the removal of non-native herbivores and the maritime climate around the Channel Islands may buffer some of the impacts of the regional drought. The MODIS sensors appears appropriate for identifying landscape patterns, time series, change detection maps, and the potential impacts from climate change for each park. Results suggest that all National Park landscapes and vegetation types can be inventoried at a 250 m resolution and monitored at a high temporal resolution.

Oak habitat recovery on California's largest islands: Scenarios for the role of corvid seed dispersal

Abstract Seed dispersal by birds is central to the passive restoration of many tree communities. Reintroduction of extinct seed dispersers can therefore restore degraded forests and woodlands. To test this, we constructed a spatially explicit simulation model, parameterized with field data, to consider the effect of different seed dispersal scenarios on the extent of oak populations. We applied the model to two islands in California's Channel Islands National Park (USA), one of which has lost a key seed disperser. We used an ensemble modelling approach to simulate island scrub oak (Quercus pacifica) demography. The model was developed and trained to recreate known population changes over a 20‐year period on 250‐km2 Santa Cruz Island, and incorporated acorn dispersal by island scrub‐jays (Aphelocoma insularis), deer mice (Peromyscus maniculatus) and gravity, as well as seed predation. We applied the trained model to 215‐km2 Santa Rosa Island to examine how reintroducing island scrub‐jays would affect the rate and pattern of oak population expansion. Oak habitat on Santa Rosa Island has been greatly reduced from its historical extent due to past grazing by introduced ungulates, the last of which were removed by 2011. Our simulation model predicts that a seed dispersal scenario including island scrub‐jays would increase the extent of the island scrub oak population on Santa Rosa Island by 281% over 100 years, and by 544% over 200 years. Scenarios without jays would result in little expansion. Simulated long‐distance seed dispersal by jays also facilitates establishment of discontinuous patches of oaks, and increases their elevational distribution. Synthesis and applications. Scenario planning provides powerful decision support for conservation managers. We used ensemble modelling of plant demographic and seed dispersal processes to investigate whether the reintroduction of seed dispersers could provide cost‐effective means of achieving broader ecosystem restoration goals on California's second‐largest island. The simulation model, extensively parameterized with field data, suggests that re‐establishing the mutualism with seed‐hoarding jays would accelerate the expansion of island scrub oak, which could benefit myriad species of conservation concern.

Bringing Santa Rosa Island into Channel Islands National Park: The Written Documents 1979–1987

The National Park Service (NPS) purchased Santa Rosa Island from private landowners Vail & Vickers in 1986. Immediately following the purchase, NPS personnel stated that they and the former landowners were negotiating a 5- to 10-year phaseout of cattle ranching and hunting of introduced deer and elk. Later, NPS staff stated that the former landowners had a 25-year right to presale land uses. This unsubstantiated “right” became the justification for the NPS issuing a series of permits that continued the operations of the former landowner. Over time, questions arose regarding the environmental impacts of the cattle, deer, and elk on Santa Rosa Island's natural and archeological resources and the restricted public use of the island. Approximately 10 years after purchasing the island, the National Park Service was sued by an environmental group. Vail & Vickers countersued. The litigation brought to light the written documents associated with the purchase of the island. The court cases were settled through a voluntary agreement which directed a rapid end to grazing of cattle and a phased reduction of deer and elk. This paper examines the written documents from 1979 to 1987, which is the period contemporaneous to the establishment of Channel Islands National Park, the sale of Santa Rosa Island, and the initiation of island management by the National Park Service. Later documents and statements will be compared to the contemporaneous documents to better understand the controversies, public perceptions, and lawsuits.

Quaternary sea-level history and the origin of the northernmost coastal aeolianites in the Americas: Channel Islands National Park, California, USA

Along most of the Pacific Coast of North America, sand dunes are dominantly silicate-rich. On the California Channel Islands, however, dunes are carbonate-rich, due to high productivity offshore and a lack of dilution by silicate minerals. Older sands on the Channel Islands contain enough carbonate to be cemented into aeolianite. Several generations of carbonate aeolianites are present on the California Channel Islands and represent the northernmost Quaternary coastal aeolianites on the Pacific Coast of North America. The oldest aeolianites on the islands may date to the early Pleistocene and thus far have only been found on Santa Cruz Island. Aeolianites with well-developed soils are found on both San Miguel Island and Santa Rosa Island and likely date to the middle Pleistocene. The youngest and best-dated aeolianites are located on San Miguel Island and Santa Rosa Island. These sediments were deposited during the late Pleistocene following the emergence of marine terraces that date to the last interglacial complex (~120,000yr to ~80,000yr). Based on radiocarbon and luminescence dating, the ages of these units correspond in time with marine isotope stages [MIS] 4, 3, and 2. Sea level was significantly lower than present during all three time periods. Reconstruction of insular paleogeography indicates that large areas to the north and northwest of the islands would have been exposed at these times, providing a ready source of carbonate-rich skeletal sands. These findings differ from a previously held concept that carbonate aeolianites are dominantly an interglacial phenomenon forming during high stands of sea. In contrast, our results are consistent with the findings of other investigators of the past decade who have reported evidence of glacial-age and interstadial-age aeolianites on coastlines of Australia and South Africa. They are also consistent with observations made by Darwin regarding the origin of aeolianites on the island of St. Helena, in the South Atlantic Ocean, more than a century and a half ago.