Scott W. Starratt

Bouse Formation in the Bristol basin near Amboy, California, USA

Limestone beds underlain and overlain by alluvial fan conglomerate near Amboy, California, are very similar in many respects to parts of the Bouse Formation, suggesting that an arm of the Pliocene Bouse water body extended across a wide part of the southern Mojave Desert. The deposits are north of the town of Amboy at and below an elevation of 290 m, along the northern piedmont of the Bristol “dry” Lake basin. The Amboy outcrops contain the Lawlor Tuff (4.83 Ma), which is also found in an outcrop of the Bouse Formation in the Blythe basin near Buzzards Peak in the Chocolate Mountains, 180 km southeast of Amboy. Bouse exposures near Amboy are ∼3.4 m thick, white, distinctly bedded, with limestone and calcareous sandstone as well as stromatolite mounds; we interpret these as nearshore deposits. The Bouse at Amboy contains ostracodes, diatoms, and mollusks that indicate saline lake or estuarine environments with an admixture of fresh-water forms. Along with wading bird tracks and a spine from a marine fish, these fossils suggest that the deposits formed in saline waters near a fresh-water source such as a perennial stream. Beds of the outcrop dip southward and are 113 m above the surface of Bristol Playa, where similar age sediments are buried 270+ m deep, indicating significant faulting and vertical tectonics in this part of the Eastern California Shear Zone during the past 5 m.y. Confirmation of the Bouse Formation at Amboy strengthens previous assignments to the Bouse Formation for mudstones in driller logs at Danby “dry” Lake, California, and suggests that areally extensive arms of the Bouse water body were west of the Blythe basin. The Bristol basin arm of the lower Bouse basin probably was restricted from the main water body by narrow passages, but Bouse sediment there is similar to that in the Blythe basin, suggesting generally similar water chemistry and environmental conditions. Examining the degree to which Bouse deposits in the western arms differed from Bouse deposits in the Blythe basin offers an approach to test whether the southernmost Bouse water body was deposited in an estuarine or lacustrine setting.

Late Quaternary paleoceanography of the Pervenets Canyon area of the Bering Sea: evidence from the diatom flora

Sediments from three gravity cores from an east-west shelf-to-slope transect along the axis of Pervenets Canyon in the northern Navarin basin, Bering Sea were analyzed for diatoms. The diatom floras present in the cores were divided into four assemblages following Sancetta (1981). The Bering Basin (deep water open ocean) and Sea Ice (ice cover at least six months per year) Assemblages were dominant in each core. The taxa that comprise the Bering Shelf Assemblage (continental shelf) indicate that downslope transport plays only a minor part in the development of the thanatocenoses. The presence (up to 10% of the total valve count) of the Productivity Assemblage, which consists mainly of poorly silicified, easily dissolved taxa, indicates that nutrient flux is relatively high in the region. Several taxa can be used as proxy indicators for specific water masses. Neodenticula seminae (Simonsen & Kanaya) Akiba & Yanagisawa is indicative of Holocene open marine (deep water) conditions. Nitzschia cylindra (Grunow...

Latest Quaternary foraminifers and sediment transport in Pervenets Canyon, Bering Sea

A combination of microfossil and sediment analysis has been used in an attempt to understand oceanographic processes and the late Quaternary history of the Pervenets Canyon region. The primary sedimentation process in Pervenets Canyon is downslope transport. Near the shelfbreak, there is evidence of turbidite and debris-flow activity, but at the distal end of the upper canyon and on the continental slope there is no macroscopic evidence for these processes. Analysis of the foraminiferal assemblages shows that the fauna is 97.6% from the Suborder Rotaliina and about 2.0% from the Suborder Textulariina. The Suborder Miliolina accounts for approximately 0.4% of the fauna. The Pervenets Canyon fauna is most similar to other faunas from the Bering Sea, indicating a North Pacific Ocean influence on the fauna. Foraminiferal abundance and species diversity vary widely in the samples studied. The major factors controlling these values are downslope transport of sediment, disintegration of arenaceous taxa, dissolution of calcareous taxa, and diversity limited by low-oxygen bottom waters. Downslope transport of shelf species is indicated by the presence of Elphidium clavatum and E. excavatum. Shallow-shelf and low-oxygen foraminiferal faunas are often intermixed in the samples. The distribution of these low-oxygen faunas in Core 81-65 suggests that the oxygen-minimum zone fluctuated with sea level.

International Limnogeology Congress (ILIC6), Reno USA, special issue on new limnogeological research focused on pre-Holocene lake systems

The 6th International Limnogeology Congress (ILIC6) of the International Association of Limnogeology (IAL) was held in Reno, Nevada, USA in 15–19 June 2015. The four day meeting was highlighted by eight keynote addresses highlighting cutting-edge research in limnology, paleolimnology, and limnogeology. More than 140 posters were presented on topics ranging from contaminant histories of lakes, the role of groundwater in lake processes, mineral formation in lake sediments, terminal lake evolution, paleoclimate and paleohydrologic processes, volcanic emissions from lakes, as well as the biological and chemical evolution of lake systems. The ages of the lacustrine systems presented ranged from Mesoproterozoic Era saline lake sediments to modern lakes. The abstract volume and field trip guide for the meeting is available at Rosen et al. (2015) and Rosen (2015), respectively. The successful congress brought together a wide variety of academic, government, and industry participants from 20 countries and all continents except Antarctica. The structure of the meeting, with keynotes talks spread throughout the meeting, stimulated hours of discussion in the poster hall. Since its founding in 1993 by Dr. Elizabeth Gierlowski-Kordesch and a handful of other limnogeologists, IAL was led by Beth until her untimely death in May 2016. A tribute to Beth and her great work can be found at: http://link.springer.com/article/ 10.1007/s10933-016-9915-1 and http://ial.strikingly. com/. As ILIC6 was Beth’s last ILIC meeting, it is fitting that we devote space to acknowledge Beth’s contribution to ILIC and IAL, and her role as a friend and colleague. Without Beth there would be no ILIC and no IAL. In addition, there would also be no Limnogeology Division of the Geological Society of America. Beth convinced the scientific community that lake-focused research organizations are important, and will continue to be important into the future. Beth was more than just a colleague to many of us, as she was also a great friend, mentor, and a steadfast promoter of limnogeology as a discipline (Fig. 1). One of us (Michael Rosen) knew Beth for 30 years, and in fact, it was on a 10-day 1986 field trip at the International Association of Sedimentology meeting in Canberra, Australia that we met. On this trip, we spent many days viewing the lakes of the Australian interior including Lake Eyre, Lake Frome, and many other lakes with long periods of time in the car and at outcrops for discussion. On a field trip of that length, it is easy to get to know everyone on the trip pretty well. Everyone on the trip already shared a common interest M. R. Rosen (&) US Geological Survey, Carson City, NV 89701, USA e-mail: mrosen@usgs.gov

Use of Mussel Casts from Archaeological Sites as Paleoecological Indicators: An Example from CA-MRN-254, Marin County, Alta California

Abstract Archaeological investigations at prehistoric site CA-MRN-254 at the Dominican University of California in Marin County, California, revealed evidence of Native American occupation spanning the past 1,800 years. A dominant source of food for the inhabitants in the San Francisco Bay area was the intertidal, quiet-water dwelling blue mussel (Mytilus trossulus), although rare occurrences of the open coast-dwelling California mussel (Mytilus californianus) suggest that this species was also utilized sporadically. On rare occasions, cultural horizons at this site contain abundant sediment-filled casts of the smaller mussel Modiolus sp. These casts were formed soon after death when the shells filled with sediment and were roasted along with living bivalve shellfish for consumption. Thin sections of these mussel casts display sedimentological and microbiological constituents that shed light on the paleoenvironmental conditions when they were alive. Fine-grained sediment and pelletal muds comprising these casts suggest that the mussels were collected in a low energy, inner bay environment. The rare presence of the diatoms Triceratium dubium and Thalassionema nitzschioides indicate more normal marine (35 psu) and possibly warmer conditions than presently exist in San Francisco Bay. Radiocarbon dating of charcoal associated with the mussel casts containing these diatoms correlates with a 600-year period of warming from ca. A.D. 700–1300, known as the Medieval Climatic Anomaly. Results of this mussel cast study demonstrate that they have great potential for providing paleoenvironmental information at this and other archaeological sites.

Foreword: A virtual congress on palaeolimnology—palaeolimnological proxies as tools for environmental reconstruction in fresh water

The motivation for collecting recent knowledge in a special issue of Hydrobiologia derives from the recognition of the importance and applicability of palaeolimnological tools to help in defining ‘‘reference conditions’’ as designated within the Water Framework Directives and estimating influence of global climate change on surface waters. This volume was developed by inviting contributions from prominent experts in their respective fields. The compilation not only presents papers on palaeolimnological studies, focusing mostly on Eastern and Central Europe but also includes results from other regions. The use of palaeoecological analyses of sediments has a long tradition in Central Europe. In the nineteenth century, Lajos Lóczy (1849–1920) organized a systematic scientific research on Lake Balaton, the largest shallow lake of the region, and published the series of booklets (Lóczy 1897–1920) which are considered milestones in the development of limnology as a separate branch of science and which are comparable to Forel’s (1841–1912) seminal scientific heritage (Forel, 1892). Another milestone in the development of palaeolimnology was the first palaeolimnologial meeting which was held in Hungary in 1967. This meeting included some of the most prominent limnologists in the world including G.E. Hutchinson, D.G. Frey (Chairman), Nina V. Korde, D.A. Livingstone, O. Sebestyén, and W. Tutin who together formed the organizing committee. This committee decided to hold the symposium at the Biological Research Institute, Tihany, Hungary. The meeting profited from the excellent facilities and made the attendance of scientists from socialist countries possible. This location was also appropriate in celebrating the long tradition of geological and limnological studies on the lake including the early Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water