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Margaret D. Foster

Publications and source records attributed to Margaret D. Foster.

15 recordsLinked to original sources
USGS2014

A study of salt‐water encroachment in the Galveston Area, Texas

A survey of the ground‐ water resources of the region in which Houston and Galveston are situated was started in December 1930 by the United States Geological Survey in cooperation with the Texas Board of Water Engineers. In connection with this survey a special study is being made of the geochemical relations of the ground‐waters of an area about 25 miles wide and 90 miles long, extending from Galveston northwestward through Houston. This study considers the influence on the ground‐waters of the age and degree of weathering of the outcrop formations, base‐exchange materials, salt ‐domes, and salt ‐ water encroachment . In this paper, however, attention is confined to salt ‐ water encroachment along the line from Galveston to Houston (Fig. 1).

Texas↗
USGS1963

The atomic ratios of natural ferruginous biotites with reference to 'the stability relations of the ferruginous biotite, annite'

The atomic ratios given by Eugster and Wones (1962) for analyses of high FeO-low MgO micas cited by Foster (1960) are in error. The recalculated atomic ratios herein presented show that only three of the thirteen have low (OH+F), and only one has characteristics that may possibly be due to loss of water during determination. None of the analyses exhibit characteristics suggestive of oxidation of iron and loss of H, as in progression towards oxyannite. The average recalculated octahedral occupancy is 2.69, not 2.91 as in the previous calculation. The differences between atomic ratios calculated on the basis ot determined H 2 O + and F and those calculated on the basis of the theoretical O 10 (OH) 2 content are not great enough to change the essential compositional character of these micas as interpreted by Foster (1960). However, they do affect significantly the calculated octahedral occupancy.

Journal of Petrology↗
USGS1955

The relation between composition and swelling in clays

The phenomenon of swelling is associated with the hydration of clays; however, all clays do not swell when hydrated. those of the kaolin group, for example, exhibit little or no swelling on hydration. Sodiwm montmoillonite, on the other hand, characteristically swells in water to many times its dry volume. Calcium and magnesium montmorillonite and the hydrous micas, or so called illites, fall between these two extremes in swelling properties, but are, in general, much closer to kaolinite than to sodium montmorillonite in their increase in volume on hydration. These differences in the swelling characteristics of different clays may be related to their chemical composition, to the kind and degree of isomorphous replacements in their structure, and to the amount and nature of their associated exchangeable cations.

Open-File Report↗
USGS1953

Geochemical studies of clay minerals III. The determination of free silica and free alumina in montmorillonites

Determination of free silica by the method proposed made possible the derivation of logical formulas for several specimens of montmorillonites for which the formulas could not be derived from the analyses alone. Other montmorillonites, for which logical formulas could be derived from their analyses, were found to contain small amounts of free silica or free alumina. Others were found to contain neither free silica nor free alumina. The method consists of the following steps: (1) digestion of 1 g of the specimen with 0.5 N NaOH solution in a covered platinum crucible or dish on a steam bath for 4 hrs, stirring the mixture at 30-min intervals, (2) filtration of the undissolved material, followed by washing several times with 1% NaOH solution, (3) neutralization of the filtrate with HCl, addition of 5 ml HCl in excess and determination of SiO and Al 2 O 3 in the usual way and (4) calculation of the amount of free SiO 2 or free Al 2 O 3 if any and the amount of attack of the clay structure by the treatment from the ratio of SiO 2 to Al 2 O 3 dissolved and the ratio of SiO 2 to Al 2 O 3 obtained on analysis. Tests with 5% Na 2 CO 3 solution, the reagent formerly used for the solution of free SiO 2 in rocks and minerals, showed that solution of opal by this reagent is always fractional, never complete, no matter how small the amount present or how long the period of treatment. Re-treatment of the sample results in 90–95% solution if 10 mg or less of opal is present, but for larger amounts of opal the percentage dissolved decreases as the amount present increases. On the other hand, 75 ml of 0.5 N NaOH completely dissolves as much as 400 mg of opal in 4 hrs digestion in a covered platinum crucible or dish, on a steam bath. However, a weaker solution or a shorter period of digestion does not effect complete solution. The same amount (75 ml) of 0.5 N NaOH also dissolves 90 mg of cristobalite and 57 mg of quartz having a grain size of less than 2 microns. Use of NaOH also permits determination of the amount of alumina dissolved, and estimation of the extent to which the clay structure was attacked by the treatment.

Geochimica et Cosmochimica Acta↗
USGS1950

The origin of high sodium bicarbonate waters in the Atlantic and Gulf Coastal Plains

Some sodium bicarbonate waters at depth in the Atlantic and Gulf Coastal Plains have the same bicarbonate content as the shallower calcium bicarbonate waters in the same formation and appear to be the result of replacement of calcium by sodium through the action of base-exchange minerals. Others, however, contain several hundred parts per million more of bicarbonate than any of the calcium bicarbonate waters and much more bicarbonate than can be attributed to solution of calcium carbonate through the action of carbon dioxide derived from the air and soil. As the waters in the Potomac group (Cretaceous) are all low in sulphate and as the environmental conditions under which the sediments of the Potomac group were deposited do not indicate that large amounts of sulphate are available for solution, it does not seem probable that carbon dioxide generated by chemical or biochemical breakdown of sulphate is responsible for the high sodium bicarbonate waters in this area. Sulphate as a source of oxygen is not necessary for the generation of carbon dioxide by carbonaceous material. Oxygen is an important constituent of carbonaceous material and carbon dioxide is a characteristic decomposition product of such material—as, for example, peat and lignite. Experimental work showed that distilled water, calcium bicarbonate water, and sodium bicarbonate water, after contact with lignite, calcium carbonate, and permutite (a base-exchange material), had all increased greatly in sodium bicarbonate content and had become similar in chemical character and in mineral content to high sodium bicarbonate waters found in the Coastal Plain. The tests indicated that carbonaceous material can act as a source of carbon dioxide, which, when dissolved in water, enables it to take into solution more calcium carbonate. If base-exchange materials are also present to replace calcium with sodium, a still greater amount of bicarbonate can be held in solution. The presence of carbonaceous material, together with calcium carbonate and base-exchange minerals in a formation is, therefore, sufficient to account for the occurrence in it of high sodium bicarbonate waters.

Geochimica et Cosmochimica Acta↗