At the Last Glacial Maximum, Santa Rosae was approximately four times larger than the combined area of the present-day islands, but was still separated from mainland California by 2—4 km at the closest point [ 73 ]. The Mediterranean climate of the islands does, however, promote ecosystems which are susceptible to burning even if they lack natural ignition sources [ 9398 ]. A synthesis of 35 palaeofire records from over North America identified a general increasing charcoal influx trend throughout the LGIT, which halted during the Younger Dryas [ 70 ].
The endemic Channel Islands pygmy mammoth Mammuthus exilis also became extinct during this interval, with the last dated evidence of mammoths overlapping the radiocarbon ranges proposed for Arlington Man approx. More recently, Kennett et al. Less-secure evidence of a human presence in the Americas during the two millennia before Clovis approx. One increasingly important approach is to investigate very long Quaternary records to improve existing knowledge of fire history over long timescales, including over multiple glacial—interglacial cycles.
Charcoal in fluvial sediments cannot be interpreted in this way, as both deposition rates and sediment textures may dating in DC channel islands ificantly. Proponents of this idea suggest that even small transient human populations could have had broad impacts on ignition-limited portions of the landscape [ 41 ].
A unifying sedimentary charcoal record is presented from Arlington Canyon, Santa Rosa Island, based on over 20 detailed sedimentary sections from eight key localities. The Late Pleistocene Clovis culture is the oldest well-defined archaeological techno-complex of North America and is thought to have appeared ca Despite the fairly short interval, Clovis technology is found over a large spatial range [ 49 ].
Streams and floodplains are also landscape systems that humans would have regularly used and indeed often also contain archaeological materials. The exact timing of human arrival in the Americas remains uncertain. Because these records minimize local variations, they contribute to regional and global syntheses of charcoal patterns over time e. Island settings have long been thought to be particularly sensitive to environmental changes, particularly to invasive species including humans.
Radiocarbon dating of 49 such fragments has allowed inferences regarding the fire and landscape history of the Canyon ca 19—11 ka BP. A ificant period of charcoal deposition is identified approximately 14— ificant evidence exists for human use of fire dating as far back as 0. The majority of Quaternary charcoal records covering this time come from lacustrine or peat bog sequences, mostly with relatively straightforward depositional histories, allowing the construction of charcoal statistics such as charcoal accumulation rates CHAR [ 24 ].
Arlington Canyon itself is incised into a sequence of uplifted Quaternary coastal terraces [ ]. Over four field seasons, eight key localities have been identified, systematically described and sampled for palaeoenvironmental analysis see figure 2 for key dated sections and the electronic supplementary material for more information.
The area of interest in this study is Arlington Canyon figure 1 which lies on the NNW side of Santa Rosa Island, with nearly continuous Late Quaternary fluvial deposits stretching 4 km from the mouth of the canyon. Recent studies have suggested that the first arrival of humans in the Americas during the end of the last Ice Age is associated with marked anthropogenic influences on landscape; in particular, with the use of fire which, would have given even small populations the ability to have broad impacts on the landscape.
These authors do, however, note a steep increase in charcoal influx around This coincides with the appearance of Clovis people; however, it is suggested that the range of sites and the high elevation of some of those sites make a causal link to humans unlikely [ 70 ]. Understanding the impact of these early people is complicated by the dramatic changes in climate occurring with the shift from glacial to interglacial conditions. Such evidence of direct human interaction with fire see also [ 5 ] is rare in the archaeological record, particularly at open, rather than cave or more sheltered, sites [ 6 ].
Within this investigation, we look to use these more complex sedimentary environments, specifically a fluvial fill sequence, attempting to answer questions surrounding the potential presence or absence of anthropogenic fire als. If the address matches an existing you will receive an with instructions to retrieve your username. Less attention has been focused on understanding fire regimes over millennial timescales recorded in more complex sedimentary environments, such as fluvial deposits, probably because depositional heterogeneity precludes simple age models and generation of statistical indices such as CHAR.
This approach allows detailed comparison between climatically similar periods e. Dating in DC channel islands these difficulties, we here attempt to test the extent of anthropogenic influence using the California Channel Islands as a smaller, landscape-scale test bed. This is unfortunate as these settings have long been recognized as rich sources of archaeological information e. More controversial is the suggestion that the first arrival of humans in the Americas during the end of the last ice age can be associated with non-trivial anthropogenic influences on landscape, in particular with the use of fire [ 4142 ].
Although marine records are undeniably valuable, they also have limitations, such as complex or undefined charcoal source areas.
However, long terrestrial records are often limited geographically, particularly in areas that have undergone repeated Quaternary glaciation. Orr discovered two human femora deposited in fluvial sediments at the mouth of Arlington Springs Canyon. An example of this is a sharp vegetation shift from herb tundra to shrub tundra associated with a sharp increase in burning occurring 14—13 ka cal BP [ 67 ].
In summary, detecting the use of fire by the first populations entering North America is complicated by i the nature of wildfire, which is sporadic and difficult to predict on short timescales; ii the wide range of Pleistocene environments and mosaic landscapes present over North America; and iii uncertainties in the precise timing of human arrival in different regions.
Late glacial fire histories are most often based upon sequences where sediments were deposited in a largely uniform manner, such as in lakes, with constant sediment accumulation rates and charcoal that are calculated against volume and time e. Google Scholar.
The Western Transverse Ranges region of coastal California, of which these islands are a part, experiences few convective storms during the summer and relatively moist winters, which in some of the lowest lighting-induced fire frequency in North America [ 3697 ].
Marine records typically have more straightforward depositional histories i.
Archaeological material is widespread and abundant on the Northern Channel Islands, including evidence early in the record from Daisy Cave and Cardwell Bluffs on San Miguel Island and sites and from the northwest side of Santa Rosa Island shown in figure 1 [ 78 — 82 ]. The much-studied archaeological record and rich sedimentary record of the Northern Channel Islands make for an excellent test bed for considering the impacts of the first human arrival upon fire regimes. The Northern Channel Islands contain extensive thick and extensive Quaternary deposits as well as evidence of human occupation fully spanning the Holocene.
The Late Pleistocene to Holocene sedimentary deposits form a fluvial fill terrace that was subsequently incised, exposing vertical to near-vertical cliff sections, often approximately 20—30 m in height [ 92 ]. The chronological data from these sites have been used within this study see Material and methods.
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Detecting the clear arrival of people and the associated shift in fire regime in this region was helped by i New Zealand's low background of natural wildfire and ii the relatively stable climate during this period. Here, we present radiocarbon which refine the temporal understanding of these sediments, an important goal on the way to building a more robust stratigraphy [ ], as well as providing insights to the temporal extent of wildfire on the Northern Channel Islands of California.
These outcrops are widespread through the canyon, allowing detailed sampling and analysis. These two steps in the continental-scale climate record mostly track with the known climatic shifts of this period.
These pollen assemblages document widespread conifer forests during the Late Pleistocene, probably existing until ca 12 cal ka BP, when the predominant conifer cover was replaced by mixed grassland and scrub communities [ 788586 ]. Despite these challenges, reconstructing fire history from these environments has advantages, in particular dating in DC channel islands able to directly connect the charcoal record to geomorphic responses to fire [ 32 — 35— ].
Before outlining our work in detail, first the North American context is introduced, in terms of the key environmental and archaeological evidence and also the complexities of investigating human—fire interactions during this timeframe. Here, we investigate the Arlington Canyon sedimentary sequence on Santa Rosa Island because i it is the canyon from which the Arlington Springs Man remains were recovered [ 74 ], and it is thus closely associated with the earliest evidence of human presence on the islands; ii sedimentary charcoal in Arlington Canyon has been noted by several research groups [ 9295 ]; and iii although much attention has been focused on single isolated sites Arlington Springs by Johnson et al.
Find this author on PubMed. This is absolutely necessary because of the complexity of the various depositional environments present in the canyon, in particular in understanding its fluvial facies and architecture. Several workers have noted charcoal fragments present in the extensive fluvial and alluvial fill sequences of the Northern Channel Islands, but this palaeofire record has been only minimally studied [ 89 — 93 ]. Alternatively, marine records are increasingly used to identify potential anthropogenic burning in the past e.
Thus, it is always desirable to combine these data with fire records from proximal terrestrial sequences. Online version in colour. It is well understood that intentional landscape burning has been practiced by humans in North America over much or all of the Holocene [ 36 — 40 ]. By ca ka BP, similar evidence of hearths is found at sites across Europe, including Beeches Pit in eastern England, which also includes the suggestion of fireside stone tool production [ 34 ].
Whereas modern hunter—gatherer communities globally use fire at the landscape scale [ 7 — 11 ], understanding how fire was used as a tool by past human populations is a complex task, particularly in geographical regions with abundant natural ignition sources, including Mediterranean climates. The Northern Channel Islands currently experience fairly low levels of natural wildfire, with few events recognized in the recent past [ 96 ].
If the address matches an existing you will receive an with instructions to reset your password. Often, secondary geomorphic effects associated with wildfire, such as post-fire erosion, are preserved in this part of the landscape sedimentary system [ 32 — 35 ]. There are many challenges of interpreting microcharcoal fragments in palaeorecords [ 20 ]; studies in pollen source areas are also informative, with some suggesting that marine pollen records are heavily biased towards pollen from higher mountain areas and river outflows [ 2122 ].
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Fire history on the california channel islands spanning human arrival in the americas
This sensitivity is due to resource limitations and because endemic flora and fauna have been isolated from natural competition for long periods of time. The climate of the Northern Channel Islands during the LGIT was moister and cooler than the present day [ 788586 ], which promoted the mosaic woodland systems observed in the pollen and palaeobotanical record, and probably further reduced the potential for wildfire events compared with the present [ 9899 ].
In particular, the Younger Dryas cold event ca Against the backdrop of these broad-scale climatic events, diachronous changes in vegetation types, burning patterns and megafauna populations have been suggested as evidence of human impacts from Alaska to southern parts of North America see [ 41 ] for full discussion. Other authors have also noted charcoal spikes following reductions in megaherbivore populations and resultant effects on fuel-load changes, and suggest that these may be fire-regime shifts indirectly related to human activity [ 6869 ].
This uncertainty relates to both chronological uncertainties usually related to radiocarbon dating as well as the accidental nature of the archaeological record, which includes variable and often ificant lag times between first arrival and first evidence [ 71 ]. Understanding the impact of the human vanguard into North America is further complicated by the contemporaneous changes in climate during the LGIT [ 58 — 62 ]. For example, in New Zealand which was colonized approx.
Another issue is that pollen source areas may change ificantly over time in marine records [ 23 ]. In summary, the archaeological record of California's Channel Islands has become an important source of information for understanding these earliest coastal peoples [ 82 ].
For the Late Quaternary, the spatial coverage of terrestrial palaeorecords improves markedly and, during the last approximately 50 kyr, radiocarbon dating allows reasonable chronologies to be formed. The Northern Channel Islands are located off the coast of southern California and are formed of four islands ranging in size from ca 3 to km 2 ; figure 1.
A recent study by Pigati et al. Collagen from these and other associated materials, such as charcoal, have since been radiocarbon dated.
Figure 1. The palaeoenvironmental record of the Northern Channel Islands around the LGIT mostly comes from sedimentary, macrobotanical and palynological records. The exact nature of this ecosystem transition, between forested to largely open conditions, remains unclear because no continuous high-resolution pollen record has yet been studied which crosses this boundary.
This has precluded a detailed understanding of this shift and its interplay with climate change, human arrival and changing fire regimes through the onset of the Holocene.