evidence of a strong paleoearthquake in 9 1 ka cal bp interpreted from mass transport deposits western quebec northeastern ontario canada this paper reviews and expands upon stratigraphic and chronologic evidence supporting the interpretation of a strong early postglacial paleoearthquake in western quebec northeastern ontario canada event horizon mapping at dasserat dufresnoy and duparquet lakes quebec coring at chassignolle and malartic lakes quebec analysis of varve exposures near both the twin falls and frederick house dams ontario and review of published and unpublished logs of varve exposures reveal that mass transport deposits formed in or are inferred to have formed in varve year vyr 1483 relative to the timiskaming varve series and about 9 1 ka cal bp are present at numerous locations within the study area the spatial extent of the vyr 1483 mass transport deposit signature covers at least 14 600 km2 and is best explained by shaking from a paleoearthquake the magnitude of the event is estimated to be a minimum of m 7 3 which is indicative of a strong paleoearthquake the vyr 1483 paleoearthquake is one of 11 events of m 5 occurring within a 425 varve year period between 9 4 and 8 95 ka cal bp and is likely part of a period of elevated early postglacial seismicity associated with rapid crustal unloading the absence of an equivalent signature within the younger portion of the glaciolacustrine or lacustrine deposits in local lakes implies that this paleoearthquake is the strongest to occur within the study area since about 9 1 ka cal bp the highly precise correlation of widely spaced mass transport and disturbed deposits provided by varves is essential to the paleoearthquake interpretation

evidence of late glacial paleoseismicity from submarine landslide deposits within lac dasserat northwestern quebec canada abstract an integrated seismo and chronostratigraphic investigation at lac dasserat northwestern quebec identified 74 separate failures within eight event horizons horizons e and b and h and g have strong or moderately strong multi landslide signatures respectively composed of 11 23 failures while horizons f d c and a have minor landslide signatures consisting of a single or pair of deposit s cores collected at six sites recovered glacial lake ojibway varve deposits that are interbedded with the event horizons the correlation of the varves to the regional timiskaming varve series allowed varve ages or ranges of varve ages to be determined for the event horizons horizons h g e and b are interpreted to be evidence of paleoearthquakes with differing levels of interpretative confidence based on the relative strength of the multi landslide signatures the correlation to other disturbed deposits of similar age in the region and the lack or possibility of alternative aseismic mechanisms the four interpreted paleoearthquakes occurred between 9770 200 and 8470 200 cal yr bp when glacial lake ojibway was impounded behind the laurentide ice sheet during deglaciation they probably represent an elevated period of seismicity at deglaciation that was driven by crustal unloading

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

a review and analysis of varve thickness records from glacial lake ojibway ontario and quebec canada abstract varve thickness records from glacial lake ojibway provide a detailed picture of ice margin dynamics and paleohydrology for the laurentide ice sheet during the early holocene the demise of lake ojibway occurred when an ice dam of the shrinking laurentide ice sheet failed perhaps releasing enough freshwater to impede atlantic meridional overturning circulation and precipitate the 8200 cal bp climatic cooling event previously published records and new information from lacustrine sediment cores are combined to reconstruct a varve record over 2100 years long between varves numbered 1 to 1500 average rates of ice margin retreat increased from 140 m y to as high as 400 m y beginning prior to varve year 1800 and lasting to around year 2000 ice readvanced along a front at least 300 km wide during an episode called the cochrane the total distance of the advance was at least 75 km and averaged around 200 m y during the advance a series of 50 anomalously thick varves were deposited the cause of which is uncertain a widespread unconformity occurred during the end of the cochrane advance which was followed at around varve year 2060 by the return of varves which thicken abruptly unlike previous varves these varves include ice rafted pellets of lake ojibway sediment these varves may have resulted from rapid melting and calving rather than a second advance and may relate to basin re filling following a lowstand there are no direct dates on the lake ojibway varves but a sudden increase in varve thickness at year 1528 is a regional stratigraphic marker that may have resulted from glacial sediment and meltwater including lake agassiz overflow diverted from routes to the lake superior basin into the lake ojibway basin dates from the lake superior basin suggest that the diversion of this water occurred at around 9040 cal bp applying this date to varve 1528 constrains the age of the lake ojibway varves numbered 1 to 2100 to between 10 570 and 8470 200 cal bp

a review of evidence of glacially induced faulting and seismic shaking in eastern canada abstract evidence of early postglacial glacially induced seismic activity should be abundant in eastern canada which was formerly covered by the laurentide ice sheet during the late wisconsinan glaciation this review identified only two probable and at most nine possible examples of glacially induced faulting over an area of 4 million km2 a far lower number than that expected from a long term rate of background seismicity the probable sites are the holy grail scarp manitoba and the series of faults buried in the sub bottom of round lake ontario the possible nine glacially induced faults include the aspy fault nova scotia and timiskaming east shore fault ontario but there is little published information on the other seven features despite this low number the common occurrence of subaqueous mass transport deposits interbedded within or immediately overlying glaciolacustrine glaciomarine deposits in many modern lake basins strongly hints at an elevated period of glacially induced seismicity over widespread areas of eastern canada in southern quebec the age of these mass transport deposits suggests that glacially induced earthquake activity began as early as about 13 5 ka cal bp which corresponds to the time of local ice melt back this indicates that glacially induced seismicity began at the time of local deglaciation in southern quebec rather then being delayed as existing fault instability models imply it is anticipated that new candidate glacially induced or younger faults will be identified in eastern canada over the next decade or so because of the increasing availability of new high resolution data imagery sources

storage properties and seasonal variations in fine grained bed sediment within the main channel and headwaters of the river sanginjoki finland lowland catchments in finland are intensively managed promoting erosion and sedimentation that negatively affects aquatic environments this study quantified fine grained bed sediment in the main channel and upstream headwaters of the river sanginjoki 399 93 km2 catchment northern finland using remobilization sediment sampling during the ice free period may 2010 december 2011 average bed sediment storage in river was 1332 g m 2 storage and seasonal variations were greater in small headwater areas total bed sediment storage mean 1527 g m 2 range 122 6700 g m 2 at individual sites storage of organic sediment mean 414 g m 2 range 27 3159 g m 2 than in the main channel total bed sediment storage mean 1137 g m 2 range 61 4945 g m 2 storage of organic sediment mean 329 g m 2 range 13 1938 g m 2 average reach specific bed sediment storage increased from downstream to upstream tributaries in main channel reaches mean specific storage was 8 73 t km 1 and mean specific storage of organic sediment 2 45 t km 1 whereas in tributaries it was 126 94 and 34 05 t km 1 respectively total fine grained bed sediment storage averaged 563 t in the main channel and 6831 t in the catchment the proportion of mean organic matter at individual sites was 15 47 and organic carbon 4 455 g c m 2 with both being highest in small headwater tributaries main channel bed sediment storage comprised 52 of mean annual suspended sediment flux and stored organic carbon comprised 7 of mean annual total organic carbon load this indicates the importance of small headwater brooks for temporary within catchment storage of bed sediment and organic carbon and the significance of fine grained sediment stored in channels for the suspended sediment budget of boreal lowland rivers copyright 2013 john wiley sons ltd

high resolution seismic reflection profiling of neotectonic faults in lake timiskaming timiskaming graben ontario quebec canada the timiskaming graben is a 400 km long 50 km wide north west trending morphotectonic depression within the canadian shield of eastern north america and experiences frequent intraplate earthquakes the graben extends along the border of ontario and quebec connecting southward with the nipissing and ottawa bonnechere grabens and the st lawrence rift system which includes a similar structure underlying the hudson valley of the eastern usa together they form a complex failed rift system related to regional extension of north american crust during the breakup of rodinia and later pangea the timiskaming graben lies within a belt of heightened seismic activity western quebec seismic zone with frequent moderate magnitude greater than magnitude 5 earthquakes including a magnitude 6 2 in 1935 these events threaten aging urban infrastructure built on soft glacial sediments post glacial landslides along the ottawa valley suggest earthquakes as large as magnitude 7 the inner part of the timiskaming graben is filled by lake timiskaming a large 110 km long post glacial successor to glacial lake barlow that was ponded by the laurentide ice sheet 9500 years ago the effects of frequent ground shaking on lake floor sediments was assessed by collecting more than 1000 line kilometres of high resolution chirp seismic profiles late glacial lake barlow glaciolacustrine and overlying post glacial sediments are extensively deformed by extensional faults that define prominent horsts and grabens multibeam bathymetry data suggest that faults influence the morphology of the modern lake floor despite high sedimentation rates and indicate recent neotectonic deformation the lake timiskaming area provides evidence of post glacial intracratonic faulting related to recurring earthquake activity along a weak spot within the north american plate

sources of fine sediment recovered from the channel bed of lowland groundwater fed catchments in the uk abstract groundwater fed lowland permeable catchments in the uk are particularly susceptible to fine sediment accumulation on the bed of their main channel systems appropriate catchment management solutions are therefore required accurate targeting of sediment abatement strategies is however hampered by the dearth of reliable information on the principal sediment sources involved in view of this a composite fingerprinting technique incorporating uncertainty analysis has been used to investigate the primary sources of fine sediment samples recovered from a total of 18 individual sampling sites on the channel bed of the rivers frome 437 km 2 and piddle 183 km 2 dorset uk in the frome study catchment mean relative contributions from areas of woodland pasture and cultivation and from channel banks subsurface sources ranged between 1 1 6 2 10 2 42 2 44 4 81 2 and 7 2 19 4 respectively the corresponding mean relative contributions in the piddle study area were 1 1 11 4 woodland 10 2 28 4 pasture 44 2 80 2 cultivated and 7 2 21 2 channel banks and subsurface sources these findings have important implications for establishing a scientific basis for assisting the targeting of sediment management and control policies

regional hydrostratigraphy and insights into fluid flow through a clay aquitard from shallow seismic reflection data in the monteregie region east of montreal quebec canada high resolution compressional p and shear s wave reflection sections were obtained using a vibratory source and three component 3c landstreamer data acquisition system during field programs carried out in 2009 and 2010 the work was part of a strategy to improve the knowledge and understanding of groundwater resources within the glacial and postglacial sediments in the region the 100 line km of seismic profiling is an excellent example of hydrogeophysics providing detailed information on the depth to bedrock the architecture and stratigraphy and physical properties of the overlying sediments on both the regional and local scales hydrostratigraphic mapping as well as insights into fluid water and or gas transport through the surface aquitard correlations of porosity and shear wave velocity in the region also allow some estimation of the variation in subsurface porosities for hydrogeological modeling

effects of suspended sediment characteristics and bed sediment transport on streambed clogging fine sediment deposition in streambeds can reduce pore water fluxes and the overall rate of hyporheic exchange producing deleterious effects on benthic and hyporheic ecological communities to increase understanding of the factors that control the reduction of hyporheic exchange by fine sediment deposition we conducted experiments in a laboratory flume to observe changes in the rates of solute exchange and kaolinite clay deposition as substantial amounts of kaolinite accumulated in the streambed two long term experiments were conducted with durations of 14 days and 29 days use of a laboratory flume system allowed steady stream flow conditions to be maintained throughout both experiments and alternating injections of known quantities of kaolinite and a sodium chloride tracer were used to assess the effect of clay accumulation on hyporheic exchange directly in the first experiment there was no bed sediment transport and kaolinite deposition formed a highly clogged near surface layer that greatly reduced hyporheic exchange application of a fundamental model for advective hyporheic exchange indicated that the effective permeability and porosity of the streambed decreased substantially during the course of the experiment in the second experiment the kaolinite was prepared with different surface properties to be more mobile and the experiment was conducted with a small degree of bed sediment transport as a result no distinct clogged layer developed and the rate of hyporheic exchange was found to remain approximately constant throughout the experiment 29 days these results indicate that increasing fine sediment loads e g those that occur from changes in land use can have substantially different impacts on hyporheic exchange and associated ecological processes depending on the stream flow conditions the rate and frequency of bed sediment transport and the extent of interaction of the introduced fines with bed sediments copyright 2004 john wiley sons ltd

lake sediments as natural seismographs earthquake related deformations seismites in central canadian lakes abstract central canada experiences numerous intraplate earthquakes but their recurrence and source areas remain obscure due to shortness of the instrumental and historic records unconsolidated fine grained sediments in lake basins are natural seismographs with the potential to record ancient earthquakes during the last 10 000 years since the retreat of the laurentide ice sheet many lake basins are cut into bedrock and are structurally controlled by the same precambrian basement structures shear zones terrane boundaries and other lineaments implicated as the source of ongoing mid plate earthquake activity a regional seismic sub bottom profiling of lakes gull muskoka joseph rousseau ontario wanapitei fairbanks vermilion nipissing georgian bay mazinaw simcoe timiskaming kipawa parry sound and lake of bays encompassing a total of more than 2000 kilometres of high resolution track line data supplemented by multibeam and sidescan sonar survey records show a consistent sub bottom stratigraphy of relatively thick lowermost lateglacial facies composed of interbedded semi transparent mass flow facies debrites slumps and rhythmically laminated silty clays mass flows together with cratered kettled lake floors and associated deformations reflect a dynamic ice contact glaciolacustrine environment exceptionally thick mass flow successions in lake timiskaming along the floor of the timiskaming graben within the seismically active western quebec seismic zone wqsz point to a higher frequency of earthquakes and slope failure during deglaciation and rapid glacio isostatic rebound though faulting continues into the postglacial lateglacial faulting diapiric deformation and slumping of coeval lateglacial sediments is observed in parry sound lake muskoka and lake joseph which are all located above prominent precambrian terrane boundaries lateglacial sediments are sharply overlain by relatively thin rhythmically laminated and often semi transparent postglacial silty clay laminations postglacial neotectonic activity is recorded by co seismic water escape structures faults slumps and debris flows in lake simcoe above a terrane boundary and especially within lakes timiskaming and kipawa recording ongoing deformation within the wqsz high resolution seismo stratigraphic data presented here support the model that ongoing mid plate earthquake activity is a consequence of brittle deformation of the upper crust of the north american plate such activity appears to have been greatest during deglaciation but continues today

can deglaciation trigger earthquakes in n america a spherical self gravitating viscoelastic earth model is used to calculate the spatial and temporal evolution of the glacially induced lithospheric stress and fault stability in north america the predicted onset time of a pulse of earthquake activities the mode of failure and the magnitude of instability are investigated for three sites with different distance from the former ice margin it is found that glacial unloading is able to trigger paleo earthquakes within the ice margin near charlevoix 47 5 n 70 1 w and in wabash valley 38 5 n 87 w outside the ice margin however rebound stress decays away from the former ice margin thus glacial unloading is unlikely to have triggered the large m8 earthquakes in new madrid 36 6 n 89 5 w

documentation of earthquake induced disturbance of lake sediments using subbottom acoustic profiling subbottom acoustic profiling in lakes on the canadian shield and in the canadian cordillera has revealed disruptions in deltaic and lacustrine sediments that can be attributed to large historical earthquakes the timiskaming earthquake of 1935 magnitude 6 25 and the vancouver island earthquake of 1946 magnitude 7 2 triggered extensive slumping and flow of postglacial sediments in lakes located within a few tens of kilometres of the epicentres of these events there is some evidence in one of the surveyed lakes for in situ mobilization of sediment on relatively gentle slopes with minimal horizontal displacement this may be a product of liquefaction induced by coseismic shaking or displacements along faults beneath the basin in another lake widespread coseismic slumping resuspended large amounts of fine sediment which then settled out onto the lake floor to produce a texturally anomalous layer features similar to those produced by the 1935 and 1946 earthquakes can also result from a variety of non

induced stresses and fault potential in eastern canada due to a realistic load a preliminary analysis summary in order to understand the causal relation between postglacial rebound and earthquakes a simple disc load model is used to 1 calculate stresses induced in the lithosphere and mantle by glacial loading melting and postglacial rebound and 2 evaluate the effect of glacial loading rebound on the failure potential for earthquakes in the upper crust the dependence of the failure potential and the actual mode of failure on the coefficient of friction the ambient tectonic stress magnitude direction the stress due to the overlying rocks and lithospheric thickness are investigated prominent features of this paper are the inclusion of 1 a viscoelastic mantle and thus the migration of stress and 2 the ambient tectonic stress and overburden stress contributions in the calculation of the total stress field it is assumed that throughout the earth there are optimally oriented pre existing virtual faults that are initially close to but not at failure thus a time dependent quantity called dfsm related to the coulomb mohr failure criterion can be defined such that a negative value of dfsm would advocate faulting or earthquake activities whereas a positive value of dfsm would promote stability the results indicate that under all combinations of tectonic stress magnitude and overburden stress crustal loading promotes fault stability directly underneath the load upon the removal of the load thrust faulting is predicted within the ice margin if the horizontal stress s induced by the overburden is greater than or equal to the vertical component s of the overburden stress 121 where sjs under this condition theory predicts that faulting or earthquake activity should have reached a maximum immediately after deglaciation if the horizontal stress induced by the overburden is less than the vertical component of the overburden stress 1 l then theory predicts fault stability within the ice margin the theory predicts fault instability both north and south of the ice margin the mode of failure however is completely determined by the value of i the trade off between the tectonic stress magnitude and the overburden stress parameter 1 is also investigated it is shown that a larger tectonic stress magnitude can be used to compensate a smaller value of 1 the results of this analysis show that variations in the coefficient of friction lithospheric thickness and a ductile zone below the upper crust do not significantly affect the above conclusions

assessment of a rapid method for quantitative reach scale estimates of deposited fine sediment in rivers abstract despite increasing concerns about the negative effects that increased loads of fine grained sediment are having on freshwaters the need is clear for a rapid and cost effective methodology that gives precise estimates of deposited sediment across all river types and that are relevant to morphological and ecological impact to date few attempts have been made to assess the precision of techniques used to assemble data on fine sediment storage in river channels accordingly we present an investigation into the sources of uncertainty associated with estimates of deposited fine grained sediment in rivers using a sediment resuspension technique an approach that provides an instantaneous measure of deposited fine sediment surface and subsurface in terms of quantity and quality we investigated how variation associated with river type spatial patchiness within rivers sampling and individual operators influenced estimates of deposited fine sediment using this approach and compared the precision with that of visual estimates of river bed composition a commonly applied technique in rapid river surveys we have used this information to develop an effective methodology for producing reach scale estimates with known confidence intervals by using a spatially focussed sampling strategy that captured areas of visually high and low deposition of fine grained sediment the dominant aspects of small scale spatial variability were controlled and a more precise instantaneous estimate of deposited fine sediment derived the majority of the remaining within site variance was attributable to spatial and sampling variability at the smallest patch scale the method performed as well as visual estimates of percentage of the river bed comprising fines in its ability to discriminate between rivers but unlike visual estimates was not affected by operator bias confidence intervals for reach scale measures of deposited fine grained sediment were derived for the technique and these can be applied elsewhere

postglacial faulting in eastern canada nature origin and seismic hazard implications abstract at more than 70 locations in southeastern canada and the adjacent united states tiny bedrock faults displace glacial striations that are about 10 000 years old these reverse faults mostly of small displacement occur in a broad arc from western ontario to newfoundland the faults lie near the margin of the laurentian ice sheet strike generally tangential to it and imply compression nearly normal to the ene directed contemporary regional stress these observations and some age relationships suggest that the faults formed very soon after deglaciation perhaps in the first few thousand years after ice melting in each place and probably represent the release of stresses caused by flexural deformation of the upper crust although the individual offsets are small the faults are believed to be pervasive and individual outcrops reflect amounts of stress relief consistent with stresses implied by the postglacial tilt of nearby lake shorelines

impacts of land use change on patterns of sediment flux in weraamaia catchment new zealand forest clearance between the 1890s and the early 1920s subsequent scrub growth and commencement of an afforestation program in 1979 modified the pattern and rate of sediment delivery to valley floors via shallow landslides and gully complexes in a steep headwater catchment 4 8 km2 in new zealand analysis of the historical record air photograph interpretation and field survey indicates that both erosion types occurred across the catchment in the 1938 storm aggrading channel beds and widening the active channel zone in contrast a 1 in 100 year event in 1988 cyclone bola induced numerous shallow landslides but erosion of gully complexes was largely restricted to subcatchments that retained pasture and the geomorphic impact of this event on channels was small the changing volume and calibre of materials delivered to the valley floor and the distribution of gully complexes altered patterns and rates of channel adjustment after the events and the resulting sediment flux development of gully complexes maintained coupling processes with channels for periods up to 102 years forming wide channels in downstream reaches upstream downstream connectivity along the trunk stream was altered by the formation of a large debris fan at the confluence with a tributary subjected to gully complex erosion in contrast slopes subjected to shallow landslides became decoupled from channels within 10 years accelerating channel degradation and narrowing effective conveyance of a large volume of fine grained materials promoted immediate aggradation of gentle gradient channels downstream as gully complex areas stabilized following an increase in forest and scrub cover channel courses became significant sediment sources although shallow landslide activity will continue to induce intermittent aggradation in the future it is inferred that average sediment yield will continue to diminish to levels approaching those experienced prior to clearcutting and the pattern of sediment flux will recover by 2030

the first surface faulting from a historical intraplate earthquake in north america although many fault ruptures are known from the boundaries of the earth s lithospheric plates the stable interiors of continents are much less active1 worldwide only ten historical intraplate earthquakes are known to have produced surface faulting2 and none of these was in eastern north america despite the confirmed prehistoric rupture of the meers fault3 some have wondered if intraplate earthquakes in the stable north american craton might somehow be different from plate boundary earthquakes and hence fail to rupture the surface4 this is an important consideration for seismic hazard assessments when the ungava earthquake with magnitude ms 6 3 and apparent shallow depth occurred on 25 december 1989 in northern canada we and independently a johnston of memphis state university concluded that it might have produced surface faulting here we report that there was indeed a surface rupture 8 5 km long with up to 1 8 m of reverse faulting on a steeply dipping arcuate fault plane the faulting confirms the seismological process and indicates that there is a hazard from ground rupturing earthquakes in eastern north america but the poor surface expression shows that finding prehistoric fault ruptures in order to constrain seismic hazard estimates will be difficult

assessment of a seismo neotectonic origin for the new liskeard thornloe scarp timiskaming graben northeastern ontario to test an inference that the new liskeard thornloe scarp nlts timiskaming graben ontario is a deglacial postglacial seismo neotectonic fault we collected shallow geophysical data along lines

the dry puna as an ecological megapatch and the peopling of south america technology mobility and the development of a late pleistocene early holocene andean hunter gatherer tradition in northern chile abstract current scientific evidence shows that humans colonized south america at least 15 000 years ago but there are still many unknown aspects of this process including the major and minor migratory routes involved and the pattern of successive occupation of a diverse continental mosaic of ecosystems in this context the role of the andean highlands 3400 meters above sea level has been neglected because of the supposedly harsh conditions for humans including hypoxia and cold climate nevertheless the environmental and cultural resources available in the high andes constitutes an important megapatch that should be assessed in terms of human settlement patterns we review the evidence for late pleistocene early holocene hunter gatherer occupation of one part of this megapatch the northern chilean dry puna in its palaeoecological context we focus on lithic technology faunal remains radiocarbon dates and other archaeological materials related to different social activities which allow us to suggest that groups of hunter gatherers organized and adapted their way of life to highland ecosystems through logistical mobility and curatorial strategies for lithic tool kits that included projectile points and other formalized tools the morphology and technological processes involved are recognized over vast territories along the high andes we identify this material expression as the high south central andean archaic hunter gatherer tradition which also featured long distance mobile settlement systems and communication processes over this broad and distinct megapatch more speculatively we outline the hypothesis that these highland ecosystems constituted a suitable migratory route that may have been key for the early peopling of the continent and contrast it with the alternative hypothesis of the initially secondary and seasonally intermittent exploitation of this habitat by hunter gatherers dispersing along the pacific coastal corridor