THE ELECTRONIC JOURNAL OF COMBINATORICS (2014), DS1.14 References

and Computing 11. The results of 143 references depend on computer algorithms. The references are ordered alphabetically by the last name of the first author, and where multiple papers have the same first author they are ordered by the last name of the second author, etc. We preferred that all work by the same author be in consecutive positions. Unfortunately, this causes that some of the abbreviations are not in alphabetical order. For example, [BaRT] is earlier on the list than [BaLS]. We also wish to explain a possible confusion with respect to the order of parts and spelling of Chinese names. We put them without any abbreviations, often with the last name written first as is customary in original. Sometimes this is different from the citations in other sources. One can obtain all variations of writing any specific name by consulting the authors database of Mathematical Reviews a

Implications of Malthus-Boserup Ratcheting for Interpreting the Archaeological Record

Prehistoric populations across North America seem to grow exponentially, with some variation between regions. Archaeologists have explored the differences somewhat, but have not explained the differences or the sustained growth with any reference to what may be going on under the surface in a way that is relevant to all regions. I propose that environmental limits on population are shaped by what populations eat and how they acquire food, and that when populations are large enough to feel the scarcity in their environment, they change their way of life in a way that increases those limits. The model I propose is well-established, and is called the Malthus-Boserup ratcheting model. I mathematically describe the Malthus-Boserup ratcheting model using a fixed population growth rate and an array of changes in environmental limit, both in the amount of change and rate of change (or how quickly my imaginary populations change their way of life). I then simplify my descriptions of these curves using exponential curves, as archaeologists might simplify real population growth curves in much the same way. I compare the models with their exponential descriptions to form expectations for what the values in exponential curves might mean regarding the archaeological record. Despite having set a constant population growth rate, the exponential curves grow at different rates, depending primarily on the amount of change in environmental population limits. I hypothesize that a list of regions assembled in order of largest to smallest change in population limits should match a list of the same regions assembled in order of exponential growth rate. I use tools in R statistical software to describe the population growth curves in four regions using both exponential curves and summed logistic curves. I then arrange the list of regions according to both the growth rate of the exponential curves and the change in the limits found in the logistic curves. The lists do not match, which suggests that, for a variety of reasons, the exponential curves do not adequately describe the underlying Malthus-Boserup ratcheting process. I then compare the models using the Bayesian Information Criterion. Bayesian Information Criterion is an indicator that increases with both the unexplained variation in the dependent variable and the number of explanatory variables used. In this sense, when comparing models describing the same data, lower values suggest either that information retained outweighs a model’s complexity, or a model’s simplicity outweighs the amount of information lost. In all four cases, the information retained in the Malthus-Boserup ratcheting model outweighs the model’s complexity. Furthermore, the summed logistic models have parameters that researchers can interpret beyond simple rates of change

Hässeldala – a key site for Last Termination climate events in northern Europe

The Last Termination (19 000–11 000 a BP) with its rapid and distinct climate shifts provides a perfect laboratory to study the nature and regional impact of climate variability. The sedimentary succession from the ancient lake at Hässeldala Port in southern Sweden with its distinct Lateglacial/early Holocene stratigraphy (>14.1–9.5 cal. ka BP) is one of the few chronologically well‐constrained, multi‐proxy sites in Europe that capture a variety of local and regional climatic and environmental signals. Here we present Hässeldala's multi‐proxy records (lithology, geochemistry, pollen, diatoms, chironomids, biomarkers, hydrogen isotopes) in a refined age model and place the observed changes in lake status, catchment vegetation, summer temperatures and hydroclimate in a wider regional context. Reconstructed mean July temperatures increased between c. 14.1 and c. 13.1 cal. ka BP and subsequently declined. This latter cooling coincided with drier hydroclimatic conditions that were probably associated with a freshening of the Nordic Seas and started a few hundred years before the onset of Greenland Stadial 1 (c. 12.9 cal. ka BP). Our proxies suggest a further shift towards colder and drier conditions as late as c. 12.7 cal. ka BP, which was followed by the establishment of a stadial climate regime (c. 12.5–11.8 cal. ka BP). The onset of warmer and wetter conditions preceded the Holocene warming over Greenland by c. 200 years. Hässeldala's proxies thus highlight the complexity of environmental and hydrological responses across abrupt climate transitions in northern Europe

Hässeldala – a key site for Last Termination climate events in northern Europe

The Last Termination (19 000-11 000 a BP) with its rapid and distinct climate shifts provides a perfect laboratory to study the nature and regional impact of climate variability. The sedimentary succession from the ancient lake at Hässeldala Port in southern Sweden with its distinct Lateglacial/early Holocene stratigraphy (>14.1-9.5 cal. ka BP) is one of the few chronologically well- constrained, multi-proxy sites in Europe that capture a variety of local and regional climatic and environmental signals. Here we present Hässeldala’s multi- proxy records (lithology, geochemistry, pollen, diatoms, chironomids, biomarkers, hydrogen isotopes) in a refined age model and place the observed changes in lake status, catchment vegetation, summer temperatures and hydroclimate in a wider regional context. Reconstructed mean July temperatures increased between ~14.1 and ~13.1 cal. ka BP and subsequently declined. This latter cooling coincided with drier hydroclimatic conditions that were likely associated with a freshening of the Nordic Seas and started a few hundred years before the onset of Greenland Stadial 1 (~12.9 cal. ka BP). Our proxies suggest a further shift towards colder and drier conditions as late as ~12.7 cal. ka BP, which was followed by the establishment of a stadial climate regime (~12.5-11.8 cal. ka BP). The onset of warmer and wetter conditions led the Holocene warming over Greenland by ~200 years. Hässeldala’s proxies thus highlight the complexity of environmental and hydrological responses across abrupt climate transitions in northern Europe

Field-Trip Guide to Mafic Volcanism of the Cascade Range in Central Oregon— A Volcanic, Tectonic, Hydrologic, and Geomorphic Journey

The Cascade Range in central Oregon has been shaped by tectonics, volcanism, and hydrology, as well as geomorphic forces that include glaciations. As a result of the rich interplay between these forces, mafic volcanism here can have surprising manifestations, which include relatively large tephra footprints and extensive lava flows, as well as water shortages, transportation and agricultural disruption, and forest fires. Although the focus of this multidisciplinary field trip will be on mafic volcanism, we will also look at the hydrology, geomorphology, and ecology of the area, and we will examine how these elements both influence and are influenced by mafic volcanism. We will see mafic volcanic rocks at the Sand Mountain volcanic field and in the Santiam Pass area, at McKenzie Pass, and in the southern Bend region. In addition, this field trip will occur during a total solar eclipse, the first one visible in the United States in more than 25 years (and the first seen in the conterminous United States in more than 37 years)

Refining the climate, glacier, and volcanic history of Iceland during the Holocene

Iceland’s position at the confluence of major oceanic and atmospheric fronts results in a highly sensitive climate evident in both instrumental and paleo records. However, open questions still remain regarding the pre-instrumental evolution of climate, glacier, and volcanic activity at this hemispherically relevant location. This dissertation capitalizes on and merges a range of analytical techniques in an effort to refine our understanding of Icelandic climate variability, glacier extent, and tephrochronology during the Holocene epoch, with a focus on Northwest Iceland. In order to provide robust age control in our records, this research required the development of a tephrochronological framework for West Iceland, a region that lacks the otherwise widely-dispersed rhyolitic marker tephras. Glacier proxies (threshold lake sediment records and emerging dead vegetation from receding ice margins) provide firm constraints on the Holocene activity of Drangajökull, an ice cap in northwest Iceland, and high-resolution lake sediment proxy records (TOC, δ13C, C/N and biogenic silica) collected adjacent to the glacier elucidate the concomitant climate. Furthermore, we explore two lipid biomarker paleothermometers (alkenones and branched glycerol dialkyl glycerol tetraether, GDGTs) in one of these lakes and its catchment soils for the first time in Iceland to quantify the evolution of Holocene summer temperature. Similar to other Icelandic ice cap histories, our records collectively illustrate that a warm early Holocene (2 to 5 oC above modern) likely resulted in the complete demise of Drangajökull shortly after 9 ka. Subsequent to peak early Holocene summer warmth, lake sediment climate proxies indicate punctuated declines in algal productivity and increases in soil erosion alongside steadily decreasing northern hemisphere (NH) summer insolation. As summers continued to cool, Drangajökull re-nucleated by ~2.3 ka and episodically expanded to its maximum dimension during the Little Ice Age (0.7-0.1 ka), when summer temperatures are estimated to be ~1 oC below modern. Triggers for cold anomalies are linked to variable combinations of freshwater pulses from waning Pleistocene ice sheets, low total solar irradiance, explosive and effusive volcanism, and internal modes of climate variability, with cooling likely sustained by ocean/sea-ice feedbacks. In addition to the lake record, GDGTs were also applied in two other settings: a Holocene soil archive in central Iceland and in the marine realm along the North Iceland Shelf. For the latter, we also developed an Icelandic GDGT-temperature calibration based on marine surface sediment that highlights the reduced uncertainty (± 0.4 oC) achievable for local rather than global calibrations (e.g., ± 4.0 oC). Local calibrations are particularly important for areas where the temperature relationship of GDGTs deviates from the overall linear correlation observed in global calibrations (i.e., cold and warm regions), such as Iceland. Although clearly reflected in the maximum dimensions of Drangajökull, the Little Ice Age cooling is obscured in all lake, soil and marine organic geochemical records investigated in this dissertation. For the former two, the erosion of older soils, nutrients and relic GDGTs likely compromise the records and imply warmth. On the other hand, the development of thick sea ice inferred from highly branched isoprenoid biomarkers on the North Iceland Shelf insulated the subsurface waters during the peak Little Ice Age, likely preventing the ventilation of heat from below the surface layer to the atmosphere. This dissertation provides critical and nuanced observations necessary for evaluating modeling simulations aiming to forecast the poorly constrained climate of the coming century.Næmni Íslands fyrir veðurfarsbreytingum kemur fram í samfelldum veðurathugunum og veðurvísum og skýrist að einhverju leyti af stöðu landsins á skilum kaldra og tempraðra sjávar- og loftmassa, sem færast í takt við umhverfisbreytingar á Norður Atlantshafi. Samspil og þróun loftslags, jökla og eldvirkni fyrir tíma samfelldra mælinga er margslungið og margt er enn á huldu um hvernig orsakasamhengi er háttað. Mikilvægt er að rýna betur í þessa ferla til að unnt verði að bæta spár um komandi umhverfis- og veðurfarsbreytingar. Þessi ritgerð greinir frá rannsóknum þar sem fjölþættum greiningaraðferðum er beitt í því skyni að betrumbæta skilning okkar á loftslagsbreytingum, útbreiðslu jökla og myndun gjóskulaga á Íslandi á Nútíma, með áherslu á Vestfirði og Drangajökul. Nákvæm greining á gjóskulögum, sem er að finna í seti vatna sem liggja að Drangajökli, var gerð til að ná fram áreiðanlegum aldursgreiningum á vatnasetinu og veðurvísum sem í því finnast, en þetta svæði hefur skort nákvæmt gjóskutímatal hingað til. Vitnisburður jökulframrása (stöðuvatnaset og aldursgreiningar á gróðri sem hefur komið í ljós undan hörfandi jökli) hafa að geyma nákvæm gögn um virkni Drangajökuls á Nútíma, studdur af veðurvísum (TOC, δ13C, C/N og lífrænn kísill) sem finnast í seti stöðuvatnanna. Að auki var með þessu verkefni í fyrsta skipti á Íslandi beitt rannsóknum á tveimur hitastigs- og rakanæmum lífmerkjum (alkenones and branched glycerol dialkyl glycerol tetraether, GDGTs) í seti eins stöðuvatnsins og í jarðvegssniði sem er að finna á upptakasvæði þess, í þeim tilgangi að ná fram þróun magnbundins sumarhita á Nútíma. Svipað og rannsóknir á sögu og þróun annarra íslenskra jökla gefa til kynna, benda niðurstöður okkar til þess að hlýindi árla á Nútíma (á bilinu 2° til 5 °C yfir meðaltali síðustu áratuga) hafi leitt til hörfunar á forvera Drangajökuls. Fljótlega eftir að hámarki hlýnunar var náð, snemma á Nútíma, sýna veðurvísar í stöðuvatnaseti stigvaxandi hnignun í framleiðni vatnaþörunga og aukningu í jarðvegsrofi, sem svörun við hægfara lækkun sumarinngeislunar á norðurhveli jarðar. Drangajökull myndaðist á ný fyrir um 2300 árum, samhliða því að sumur tóku að kólna, og náði jökullinn hámarksútbreiðslu á litlu ísöldinni (fyrir 0,7-0,1 þúsund árum) þegar hitastig sumars er talið hafa verið ~1 °C undir meðalhita síðustu áratuga. Ástæður kaldra frávika á þessu tímabili eru tengdar minni sólarvirkni, aukinni eldvirkni (bæði sprengigosa og hraungosa) og innri breytileika veðurkerfa þar sem kólnun var viðhaldið af svörun hafs og hafíss. Hitastigs- og rakanæma lífmerkið GDGT var að auki rannsakað í tveimur öðrum umhverfum; í jarðvegssniði frá Nútíma á hálendi Íslands, og í sjávarsetkjarna sem tekinn var af landgrunninu fyrir norðan Ísland. Fyrir sjávarsetskjarnann var að auki þróaður íslenskur GDGT-hitastigskvarði, sem byggir á yfirborðssýnum teknum af sjávarbotninum og sýna niðurstöður möguleika á að ná fram minni óvissu (±0,4 °C) með slíkri staðbundinni kvörðun samanborið við hnattræna kvörðun (±4,0 °C). Staðbundin kvörðun er sérstaklega mikilvæg fyrir svæði eins og Ísland, þar sem hitastigstengsl GDGT víkur frá heildar línulegri fylgni hnattrænna kvarða (þ.e. köld og heit svæði). Þó kólnun á litlu ísöldinni endurspeglist greinilega í hámarksstærð Drangajökuls og eðlisrænum veðurvísum, kemur kólnun Litlu ísaldarinnar ekki skýrt fram í hitastigsnæma lífmerkinu (GDGT) í þeim þremur umhverfum sem hér eru til umfjöllunar (vatnaseti, jarðvegi og sjávarseti). Í fyrstu tveim tilfellunum, (þ.e. vatnaseti og jarðvegssniði), er líklegasta ástæðan rof á eldri jarðvegi frá hlýrri tíma (þ.e eldri jarðvegur hefur fokið yfir yngri jarðveg og í stöðuvatnið á hámarki litlu ísaldar), næringarefni og GDGT hafa blandast yngra efni að einhverju leyti og gefa því til kynna hlýrra hitastig en var í raun á litlu ísöldinni. Í sjávarsetinu benda lífmerkin til þess að þykkur og samfelldur hafís hafi myndast á hámarki litlu ísaldarinnar og náð að einangra sjó undir yfirborðinu og þannig komið í veg fyrir hitastreymi frá undirlögum sjávar til andrúmsloftsins. Þessi ritgerð bætir við nýjum og ítarlegum niðurstöðum sem eru mikilvægar fyrir gerð líkana sem miða að því að spá fyrir um þróun loftslags og hugsanlegar breytingar á næstu öldum.RANNIS, University of Iceland, University of Colorado Boulder, Lamont-Doherty Earth Observator

Evaluation of Late Mesozoic and Cenozoic Tectonism: Atlantic Inner Coastal Plain Margin Near Richmond, Virginia

A combined geologic, geophysical, and geomorphic analysis of the Virginia Inner Coastal Plain margin near Richmond was conducted to investigate the presence of basement structures and to evaluate their influence on the overlying sedimentary package and present-day landscape. Basement structures identified included north-northeast and northwest oriented faults that appear to bound and transect a north-northeast trending early Mesozoic basin or basins and other pre-existing zones of weakness. Observed offsets are propagated upward through the pre-Miocene strata in the form of reverse faults and flexuring. Fracture sets measured in the Petersburg Granite and overlying Coastal Plain units, stream drainage lines, and topographic linears occur in one of three to four dominant orientations (N-S, NE-SW, NW-SE, E-W) coincident with large scale structures found throughout the Virginia Coastal Plain inferring a common tectonic origin. Major drainage courses traversing the study area are also controlled by the presence of identified basement structures