Prior to about 1963 it was generally accepted that northern New England and adjacent Canada were progressively deglaciated from southeast to northwest during Late Pleistocene time. R. Chalmers and E. Antevs thought differently, but their views were not seriously considered, although their models were basically correct as we understand the deglaciation pattern today. Since about 1963 abundant evidence has accumulated that demonstrates that the Laurentide Ice Sheet was partitioned by a marine calving embayment that advanced up the St. Lawrence Lowland to the Ottawa area at least by 12,800 years B.P. This event left ice sheet remnants over much of Maine, southeastern Quebec, and probably in New Brunswick and western New England as well. Continuing research is needed to delineate the details of the final deglaciation in southeastern Quebec and Maine. Data presently available suggests that the Longfellow, White, and Boundary Mountains emerged as nunataks as early as 15,000 years ago, separating the ice sheet to the north and south. The Frontier Moraine, located on the divide between Quebec and Maine, formed at that time. Subsequently, other moraines formed as the margin of the ice sheet receded northwestward into the St. Lawrence Lowland of Quebec.

Abstract Historical production of metals in the western United States has left a legacy of acidic drainage and toxic metals in many mountain watersheds that are a potential threat to human and ecosystem health. Studies of the effects of historical mining on surface water chemistry and riparian habitat in the Animas River watershed have shown that cost-effective remediation of mine sites must be carefully planned. of the more than 5400 mine, mill, and prospect sites in the watershed, ∼80 sites account for more than 90% of the metal loads to the surface drainages. Much of the low pH water and some of the metal loads are the result of weathering of hydrothermally altered rock that has not been disturbed by historical mining. Some stream reaches in areas underlain by hydrothermally altered rock contained no aquatic life prior to mining. Scientific studies of the processes and metal-release pathways are necessary to develop effective remediation strategies, particularly in watersheds where there is little land available to build mine-waste repositories. Characterization of mine waste, development of runoff profiles, and evaluation of ground-water pathways all require rigorous study and are expensive upfront costs that land managers find difficult to justify. Tracer studies of water quality provide a detailed spatial analysis of processes affecting surface- and ground-water chemistry. Reactive transport models were used in conjunction with the best state-of-the-art engineering solutions to make informed and cost-effective remediation decisions. Remediation of 23% of the high-priority sites identified in the watershed has resulted in steady improvement in water quality. More than $12 million, most contributed by private entities, has been spent on remediation in the Animas River watershed. The recovery curve for aquatic life in the Animas River system will require further documentation and long-term monitoring to evaluate the effectiveness of remediation projects implemented.