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Stream, floodplain, and wetland restorations enhance water quality and ecological function; however, soil health is prioritized infrequently in restoration planning and monitoring. Buried, historic, hydric soils—common across U.S. mid‐Atlantic valley bottoms beneath legacy sediments—are not included in most floodplain restoration designs, though they may retain favorable biogeochemical characteristics and host legacy microbial communities that could support ecosystem recovery if exhumed and preserved. To assess the efficacy of including historic hydric soils in floodplain restoration for nitrogen (N) removal, we characterized pre‐Euro‐American settlement wetland soils buried below legacy sediments and now exposed along incised streambanks across the mid‐Atlantic. We compared carbon (C) and N contents; C:N ratios; nitrate‐N and ammonium‐N concentrations; denitrification rates; functional genes for denitrification (nosZ) and nitrification (amoA for ammonia oxidizing archaea [AoA] + ammonia oxidizing bacteria [AoB]); and phospholipid fatty acid biomasses of historic wetland soils with contemporary wetland soils before and after an 1‐year incubation in a recently restored floodplain. Compared to modern wetland soils, historic hydric soils buried by legacy sediment are less nutrient‐rich, have fewer functional genes for and lower rates of denitrification, and possess significantly less microbial biomass. Following the 1‐year incubation, many of these concentrations, rates, and gene counts increased in historic soils, though not substantially. Ultimately, our results suggest that while inclusion of historic, hydric soils and their legacy microbiomes is valuable for N‐removal in floodplain restoration, the recovery of historic, hydric soils is predictably slow, and attainment of restoration goals, such as increased denitrification, may require multiple years. [ABSTRACT FROM AUTHOR]

Author(s): Robert C. Walter (corresponding author) [1]; Richard T. Buffler [2]; J. Henrich Bruggemann [3, 4]; Mireille M. M. Guillaume [6]; Seife M. Berhe [7]; Berhane Negassi [2, 8]; Yoseph [...]

The 40Ar/39Ar radioisotopic dating technique is one of the most precise and versatile methods available for dating events in Earth's history, but the accuracy of this method is limited by the accuracy with which the ages of neutron-fluence monitors (dating standards) are known. Calibrating the ages of standards by conventional means has proved difficult and contentious. The emerging astronomically calibrated geomagnetic polarity time scale (APTS) offers a means to calibrate the ages of 40Ar/39Ar dating standards that is independent of absolute isotopic abundance measurements. Seven published 40Ar/39Ar dates for polarity transitions, nominally ranging from 0.78 to 3.40 Ma, are based on the Fish Canyon sanidine standard and can be compared with APTS predictions. Solving the 40Ar/39Ar age equation for the age of the Fish Canyon sanidine that produces coincidence with the APTS age for each of these seven reversals yields mutually indistinguishable estimates ranging from 27.78 to 28.09 Ma, with an inverse variance-weighted mean of 27.95 [+ or -] 0.18 Ma. Normalized residuals are minimized at an age of 27.92 Ma, indicating the robustness of the solution.

Single-crystal laser-fusion 40Ar/39Ar analyses on previously undatable tephra deposits provide the first reliable dates for the important hominid fossils popularly called 'Lucy' and the 'First Family,' here dated to 3.18 and 3.20 Ma, respectively. These results help to establish an age framework for hominid and biostratigraphic evolution for the fossil-rich Hadar Formation. The abundance of well-preserved vertebrate fossils at Hadar can be attributed, in part, to an unusually high sediment-accumulation rate of approximately 80 cm/ka, which might be due to increased tectonic subsidence of the Hadar basin between 3.4 and 3.2 Ma. The new dates also provide supportive evidence that the boundary ages for the Kaena and Mammoth subchrons, of the geomagnetic polarity time scale, need to be increased by as much as 4% to 5%.

The discovery of new fossils of Australopithecus afarensis, the oldest species at Maka in Ethiopia, indicates that it as a single, sexually dimorphic and ecologically different bipedal Plicone primate species. This species existed in Ethiopia and Tanzania. It shows similarities with the Lactoli holotype of A. afarensis.

Human fossils and other remains are abundant in the Konso-Gardula archaeological area in the southern part of the Main Ethiopian Rift, discovered in 1991 by the Palaeoanthropological Inventory of Ethiopia. The sediments correspond to Acheulean culture, and have been isotope dated to approximately 1.3 to 1.9 million years ago. Homo erectus was contemporary with these people, and both probably dispersed into Eurasia before the global ice movements which occurred between 0.9 and 0.7 million years ago.

The use of intra-aortic injections of 3 to 6 cc of 1 per cent procaine to prevent arterial spasm during aortography is described. It is recommended as an adjunct to aortography done under local anesthesia and may be useful as well in cases vascular disease when the procedure is done under a general anesthetic. [ABSTRACT FROM AUTHOR]

A response by Robert C. Walter and Dorothy J. Merritts to the letters to the editor about their article "Natural Streams and the Legacy of Water-Powered Mills" in the January 18, 2008 issue is presented.

Widespread deforestation, agriculture, and construction of milldams by European settlers greatly influenced valley-bottom stream morphology and riparian vegetation in the northeastern USA. The former broad, tussock-sedge wetlands with small, anastomosing channels were converted into today's incised, meandering streams with unstable banks that support mostly weedy, invasive vegetation. Vast accumulations of fine-grained "legacy" sediments that blanket the regional valley-bottom Piedmont landscape now are being reworked from stream banks, significantly impairing the ecological health of downstream water bodies, most notably the Chesapeake Bay. However, potential restoration is impaired by lack of direct knowledge of the pre-settlement riparian and upslope floral ecosystems. We studied the subfossil leaf flora of Denlingers Mill, an obsolete (breached) milldam site in southeastern Pennsylvania that exhibits a modern secondary forest growing atop thin soils, above bedrock outcrops immediately adjacent to a modified, incised stream channel. Presumably, an overhanging old-growth forest also existed on this substrate until the early 1700s and was responsible for depositing exceptionally preserved, minimally transported subfossil leaves into hydric soil strata, which immediately underlie post-European settlement legacy sediments. We interpret the eleven identified species of the subfossil assemblage to primarily represent a previously unknown, upland Red Oak-American Beech mixed hardwood forest. Some elements also appear to belong to a valley-margin Red Maple-Black Ash swamp forest, consistent with preliminary data from a nearby site. Thus, our results add significantly to a more complete understanding of the pre-European settlement landscape, especially of the hardwood tree flora. Compared with the modern forest, it is apparent that both lowland and upslope forests in the region have been modified significantly by historical activities. Our study underscores that generally overlooked subfossil leaves can provide important, local, temporally constrained paleoecological data, with much potential value in this case for stream and wetland restoration decisions in the mid-Atlantic region.