Beryllium-10 and aluminium-26 concentration and production rates in glacial deposits from the Quartermain Mountains

Many glacial deposits in the Quartermain Mountains, Antarctica present two apparent contradictions regarding the degradation of unconsolidated deposits. The glacial deposits are up to millions of years old, yet they have maintained their meter-scale morphology despite the fact that bedrock and regolith erosion rates in the Quartermain Mountains have been measured at 0.1-4.0 m/Ma. Additionally, ground ice persists in some Miocene-aged soils in the Quartermain Mountains even though modeled and measured sublimation rates of ice in Antarctic soils suggest that without any recharge mechanisms ground ice should sublimate in the upper few meters of soil on the order of 10**3 to 10**5 years. This paper presents results from using the concentration of cosmogenic nuclides beryllium-10 (10Be) and aluminum-26 (26Al) in bulk sediment samples from depth profiles of three glacial deposits in the Quartermain Mountains. The measured nuclide concentrations are lower than expected for the known ages of the deposits, erosion alone does not always explain these concentrations, and deflation of the tills by the sublimation of ice coupled with erosion of the overlying till can explain some of the nuclide concentration profiles. The degradation rates that best match the data range 0.7-12 m/Ma for sublimation of ice with initial debris concentrations ranging 12-45% and erosion of the overlying till at rates of 0.4-1.2 m/Ma. Overturning of the tills by cryoturbation, vertical mixing, or soil creep is not indicated by the cosmogenic nuclide profiles, and degradation appears to be limited to within a few centimeters of the surface. Erosion of these tills without vertical mixing may partially explain how some glacial deposits in the Quartermain Mountains maintain their morphology and contain ground ice close to the surface for millions of years.

Town law journals from Concord, Mass., 1798-1839

Seven manuscript journals written by Abiel Heywood (Justice of the Peace, town clerk, and chairman of the board of selectmen, Concord, Mass.), Nathan Brooks, William Parkman, and John L. Tuttle containing criminal records, defaulted cases, and civil actions.

Account book of David Townsend, 1774-1791

Account book kept by Dr. David Townsend (1753-1829) that records patients treated, illnesses, and fees charged in Boston, Massachusetts, and neighboring towns from 1774 to 1791. His patients included a number of soldiers and sailors, as well as figures like the French-American writer John Hector St. John (1735-1813). Townsend's treatments typically consisted of delivering cathartics or emetics. For the family of Samuel Appleton, Townsend administered smallpox inoculation in 1776, charging him 4 pounds, 4 shillings. Townsend sometimes recorded the occupation or race of the patient. For example, he attended the delivery of a child of Sappho Henshaw, "black girl," in 1786; in 1787 he attended to an unnamed "black man at [who lived at the] corner of Board Alley" in the North End of Boston. Other patients included John Hancock (1736-1793) and members of Hancock's household, as well as Federalist publisher John Fenno (1751-1798).

(Table 1) Soil density and concentration of 10Beryllium and 26Aluminium in samples from two ash deposits in the McMurdo Dry Valleys

The McMurdo Dry Valleys, Antarctica (MDV) are among the oldest landscapes on Earth, and some landforms there present an intriguing apparent contradiction such that millions of years old surface deposits maintain their meter-scale morphology despite the fact that measured erosion rates are 0.1-4 m/Ma. We analyzed the concentration of cosmic ray-produced 10Be and 26Al in quartz sands from regolith directly above and below two well-documented ash deposits in the MDV, the Arena Valley ash (40Ar/39Ar age of 4.33 Ma) and the Hart ash (K-Ar age of 3.9 Ma). Measured concentrations of 10Be and 26Al are significantly less than expected given the age of the in situ air fall ashes and are best interpreted as reflecting the degradation rate of the overlying sediments. The erosion rate of the material above the Arena Valley ash that best explains the observed isotope profiles is 3.5 ± 0.41 x 10**-5 g/cm**2/yr (~0.19 m/Ma) for the past ~4 Ma. For the Hart ash, the erosion rate is 4.8 ± 0.21 x 10**-4 g/cm**2/yr (~2.6 m/Ma) for the past ~1 Ma. The concentration profiles do not show signs of mixing, creep, or deflation caused by sublimation of ground ice. These results indicate that the slow, steady lowering of the surface without vertical mixing may allow landforms to maintain their meter-scale morphology even though they are actively eroding.

Essays on the philosophy of theism /

Spine title: The philosophy of theism.

The history of signboards from the earliest time to the present day,

Mode of access: Internet.

The causes of the war of 1792.

Bibliographical footnotes.