Archaeological geology of two flow-banded spherulitic rhyolites in New England, USA: their history, exploitation and criteria for recognition

Artifacts of spherulitic rhyolite derived from two locations in northern New Hampshire are significant to minor components of numerous Paleoindian, Archaic and Woodland archaeological sites in Maine, New Hampshire, Massachusetts, Vermont and easternmost Quebec. The two known sources of are a dike near the city of Berlin, New Hampshire, and blocks-in-till near the village of Jefferson, New Hampshire. The source near Berlin has been a known source for “Indian relics” since the middle of the nineteenth century. The second source near Jefferson New Hampshire was first recognized in 1997. Both sources are situated along prominent east–west routes between the east flowing Androscoggin River on the east and the south flowing Connecticut River on the west. Mount Jasper is located above the Dead River. The Dead River flows east and enters the Androscoggin River approximately 3 km from Mount Jasper. Passage between the Connecticut and Androscoggin Rivers would have taken the travelers directly beneath Mount Jasper. To the west, from the upper reaches of the Dead River, the portage to Head Pond is approximately 0.9 to 1.5 km. From Head Pond access to the Connecticut is by way of the North Branch Upper Ammonoosuc River. The Jefferson source is located on terraces on the northwest side of the modern Israel River. The Israel River flows west and north for approximately 25 km into the Connecticut River. To the east the Israel River rises to a divide which separates it from the east flowing Moose River, which empties into the Androscoggin. Attribution to source is based upon comparison with known outcrops which include the combined characteristics of gross lithology, weathering characteristics, and bulk mineralogy. Comparison of dike samples with artifacts also indicate that the thickness and continuity of the flow bands together with spherule characteristics, which include, size, shape, volume, microscopic structures and weathering character, further suggest a limited source.