Consideration of stratigraphic sections from five areas of northeastern Maine suggests that marked lateral lithofacies changes occur within the Ordovician and Silurian systems over very short distances. Three regionally extensive Ordovician (Caradocian-Ashgillian) lithofacies are present in the area of this study: (1) a western volcanic-graywacke-slate facies (Winterville Formation), (2) a medial slate-graywacke facies (Madawaska Lake Formation), and (3) an eastern slate-limestone-graywacke facies (lower Carys Mills Formation). The zones of gradual transition between these Ordovician lithofacies are subparallel to the trends of major structural elements. All of the lithofacies appear to have formed in relatively deep water and relatively far from cratonal source areas. The transition from Ordovician to Silurian is conformable and gradual in the eastern part of the area in contrast to abrupt and unconformable transitions in the central and western portions. Mild Taconian deformation during the latest Ordovician and earliest Silurian created western emergent areas that shed clastic debris into a continuing Silurian sedimentary basin in the east. In the eastern part of the area, continuous and fossiliferous stratigraphic successions representing almost the entire Silurian are present. The Early Silurian (Llandoverian-early Wenlockian) is represented by three principal lithofacies: (1) a western sandstone-conglomerate-slate facies (Frenchville Formation), (2) a central phyllitic slate-limestone-ironsione facies (New Sweden Formation), and (3) an eastern calcareous mudstone-limestone facies (Spragueville Formation). The Frenchville and New Sweden Formations contain material eroded from exposed Winterville and Madawaska Lake rocks in the Taconian land area(s) to the west. The Lower Silurian units are overlain conformably by thin-bedded flysch (Jemtland Formation) of late Wenlockian-early Ludlovian age that was also derived for the most part from western source areas. The youngest eastern Silurian unit is the Fogelin Hill Formation which overlies the Jemtland Formation conformably and consists of thinly interlayered red slate, green slate, and fine-grained, laminated, calcareous graywacke. In the western part of the region, the Lower and Middle Silurian are not present, and Upper Silurian sandstone, conglomerate, limestone, shale, and volcanic rocks unconformably overlie the Winterville Formation. The Upper Silurian sedimentary rocks, derived largely from the Winterville Formation, formed along irregular and possibly narrow shelves around emergent areas of the western Taconian land mass that had become largely submerged by Late Silurian time. No melange units have been found in the Ordovician and Silurian rocks of northeastern Maine to suggest the presence of a subduction zone as proposed by Bird and Dewey (1970). The Winterville volcanic rocks may be interpreted to be part of a complex island arc with a trench located outside the area to the southeast or northwest.

Abstract Quaternary mapping and drift prospecting studies were conducted in the Bathurst Mining Camp between 1993 and 1999 as part of the EXTECH-II project. Regional surficial mapping (1:50,000 scale) and till sampling were conducted in the Nepisiguit Falls area, where a total of 227 basal till samples were collected, at approximately 2-km spacing. More closely spaced samples were collected around the Halfmile Lake (520 samples) and Restigouche (265 samples) massive sulfide deposits. Ice-flow indicators (striations, grooves, and roche moutonnées) together with till fabric analyses, till clast provenance studies, till geochemistry, and the distribution of boulder erratics indicate that early glacial transport was primarily in an easterly direction. This ice flow was followed by northeastward- and southeastward- flowing ice. Minor late-stage, local ice flows followed in various directions. Evidence of north-northeast and southeast ice flows preceding the eastward flow exists in the eastern parts of the Bathurst Mining Camp. Bedrock outcrop is scarce and most of the area (>99%) is covered by unconsolidated material (till, glaciofluvial, organic, alluvial, and colluvial deposits) and preglacially weathered bedrock (regolith). A generally thin (<2 m) layer of sandy-clay greenish- to yellowish-brown, locally derived basal till covers most of the area. Geochemically anomalous till within the Bathurst Mining Camp includes east-northeastward-trending dispersal trains from the Halfmile Lake, Restigouche, and Stratmat mineral deposits. Indium, Sn, and As, and, to a lesser extent, Cu, Pb, Ag, and Zn in the <0.063-mm fraction of basal till are the best indicators of glacial dispersal in the Bathurst Mining Camp. Most till geochemical dispersal trains are short (<500 m) fans and ribbons and trend in an east-northeast direction in the northern, central, and eastern parts of the Bathurst Mining Camp and in a southeast direction in the southern part of the Bathurst Mining Camp.