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The distribution of detrital mineral cooling ages in modern sediments has been proposed as a proxy for long‐term, catchment‐averaged erosion rates in developing orogens. However, the applicability of this potentially valuable tool hinges on restrictive assumptions regarding a catchment's steady state thermal and topographic evolution. In this paper, we outline a method by which these assumptions can be tested through statistical comparisons of cooling age distributions for detrital minerals and the hypsometric curves for their source regions using cumulative synoptic probability density functions. Our approach is illustrated with new detrital muscovite 40Ar/39Ar dates from the Marsyandi River valley, in the central Nepalese Himalaya. One of three studied catchments (Nyadi Khola) showed the strong correlation of hypsometry and cooling ages expected for steady state conditions over the 11 to 2.5 Ma time frame. The pattern of mismatch between hypsometry and cooling age distribution in the other catchments suggests that spatially nonuniform and transient erosional processes may be responsible for departure from steady state. Cooling age distribution comparisons for samples collected from nearby localities, samples collected in different years, and different grain size fractions from the same sample were used to evaluate sampling fidelity over a range of spatial scales (200 to 2590 km2). We found that approximately 50 analyses from a single sediment sample adequately characterize the cooling age signal for tributary catchments with simple erosional histories. However, because of temporally and spatially transient erosion, a specific detrital sample is unlikely to adequately characterize the complex signal in trunk stream sediments that integrate information from several large tributaries.

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The use of native copper in some prehistoric cultures of North America was both extensive and technically skillful. The remains of pits sunk into every major native copper lode in the Lake Superior region (Griffin 1961; Drier and DuTemple 1961: 16; Quimby 1960: 52-63; West 1929) show that the material was mined in quantity. Float copper, found on the surface, was also used. The Indians appreciated some of the properties of copper and made use of these in shaping tools, weapons, and ornaments of high-quality workmanship. Figure 1 shows typical examples of the thousands of beautifully shaped native copper artifacts which have been found in mid-North America. The development of metallurgical techniques is usually supposed to follow a progression of hammering, annealing, melting the native metal, smelting ores, casting, and alloying. Curiously enough, the techniques of copper working in North America evolve only through the hammering and annealing stages, and apparently they remained at this level for centuries. In this paper the authors examine some of the metallurgical properties of the artifacts and the native copper from which they were made.

In a recent synthesis of style theory, Carr (1995) proposed a model based on attribute hierarchies, which reveal social patterns. The present study applies Carr's model of style to a large sample of bicymbal copper ear spools, a diagnostic “Hopewell” artifact class of the Middle Woodland period (ca. 150 B.C.—A.D. 400) in eastern North America. After ear spool attributes are defined and ranked for their visibility, a seriation of the ear spools is developed and tested for time and space correlations. Results are consistent with the interpretation that the size of social groups participating in ritual events increased over time, while the technical requirements for ear spool durability decreased. The “visibility” of ear spool attributes relates to patterns of group interaction at the level of the site, sub-region and region, thus supporting Carr's model. The model has limitations when bridging from archaeological data to ethnographic interpretations, although our results indicate that exchange of finished goods and technology was less important within the context of the Hopewell Interaction Sphere than the construction of Hopewell ideologies.

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