Christine Shultis MSc Thesis Abstract

Thesis Title: 
Quaternary Sedimentology East of Thunder Bay, Ontario; Implications for Five Paleoindian Sites

A geoarchaeological investigation was north of Highway 11/17, 34km east of Thunder Bay, Ontario.  Five archaeological sites (Mackenzie 1, Mackenzie 2, RLF, Woodpecker 1, and Woodpecker 2) and seven additional sediment exposures were examined for stratigraphic analysis to accompany the archaeological excavations.  River-mouth sediments at 268m asl and a series of deltas indicate that the study area was subaqueous while placement of the Superior lobe prevented drainage to the Superior basin.  This elevation is consistent with Lake Beaver Bay, an ice-contact lake that received glacial meltwater from the north (the Hudson Bay lobe) as well as the south (the Superior lobe).  This is demonstrated by southward and northward prograding deltaic sequences within the study area.  

As the Superior lobe made its final retreat, Lake Beaver Bay dissipated into the Superior basin marking the beginning of the Minong phase, likely around 9,900 14C yrs BP.  Additional sequences representing river-mouth, beach shoreface, and deltaic depositional environments indicate that a series of shorelines within the study area represent subsequent Minong lake levels.  The highest, and likely oldest of these strandlines is an erosional feature at 256m asl, consistent with wave-cut terraces previously identified in the Thunder Bay region.

Relative lake level drops occurred, likely due to a combination of gradual erosion of the Nadoway Point sill and isostatic rebound of the recently deglaciated land.  Beach and river-mouth sequences representing subsequent shorelines are located at 249m, 243m, and 240m asl.  Artifacts on each of these beach terraces suggest they were occupied by Paleoindian groups.

The occupation layer(s) at the Mackenzie 1 site are strongly bioturbated, although the sediment matrix is consistent with underlying beach sediments in the north and river-mouth sequences in the south.  The site is about 10,000 m2, and 378 Paleoindian projectile points were recovered along with additional bifaces, other formal and expedient tools, as well as lithic debitage.  The frequency of artifacts and site size likely indicate that Mackenzie 1 was successively occupied over an extended time period of time.  However, absence of an unconformity separating the visible stratigraphy from the massive occupation layer(s) may indicate that the site was inhabited soon after deposition ceased.  This likely places site occupation within the Minong phase (dating to ~10,500 to 9,000 cal BP). 

Artifacts recovered from the RLF archaeological site are also within a bioturbated sediment matrix consistent with underlying stratigraphy.  Lithofacies indicate that soon after the beach shoreface sediments were deposited, the beach terrace was utilized by mobile Paleoindian groups.

A shoreline at 240m asl is evidenced by a wave-cut feature and beach sediments at the Woodpecker sites, river-mouth sequences at the Mackenzie 2 site, and beach shoreface deposits at a roadcut exposure.  Presence of artifacts and charcoal within beach sediments at the Woodpecker 2 site provides evidence that occupation was contemporaneous with active beach formation.  However, the majority of recovered artifacts at Woodpecker 1 and Woodpecker 2 are associated with bioturbated sediments consistent with underlying stratigraphy.  Most likely, the Woodpecker sites were occupied along an active Lake Minong margin, and subsequently inhabited soon after the relative lake level dropped again.  The artifact matrix at the Mackenzie 2 site similarly suggests that occupation occurred soon after deposition of the underlying river-mouth sequences

Two additional exposures revealing a deltaic sequence and beach sediments suggest that the relative lake level lowered to 233m, and subsequently to 224m asl.  This lowest shoreline identified within the study area likely represents the beginning of the Post-Minong phase.

All five archaeological sites are strategically placed on beach terraces, which is consistent with most presently known Paleoindian habitations in Northwestern Ontario.  As well, The Mackenzie and Woodpecker sites likely had access to a river, making them ideal for fishing as well as hunting at the river crossings.  The study area provides additional evidence that lake margins and river-mouths were highly attractive campsites for mobile Paleoindian groups.  In addition, artifacts recovered from within beach sediments at Woodpecker 2 suggest that the Thunder Bay region was first occupied soon after deglaciation.  The Mackenzie, RLF, and Woodpecker sites were likely inhabited between about 9,900 and 9,000 14C yrs BP. 

A copy of the thesis can be downloaded here