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Based on visual observations and tests made of Georgia marble units that have been in service at the historic Minnesota State Capitol for 110 years, a fielddiscernible correlation exists between marble unit mineralogical composition and unit weathering performance. Field studies noted over the course of a five-year restoration project of the capitol exterior were used to categorize the original marble cladding into four perceptible types, which were evaluated by field testing that suggested a correlation between the textural and mineralogical differences within the marble and its long-term durability. To test this theory, field-issued repair assignments made during an exterior marble restoration project at the capitol were examined statistically. The nature and frequency of assigned repairs were compared to the type of marble from which they were originally fabricated to determine whether a correlation existed. The results of this comparison provided convincing statistical verification of the link between mineralogy and durability. This hypothesis was then verified through detailed petrographic analysis in a laboratory setting, which determined that marble consisting of a smaller, more interlocked grain configuration that was more dolomitic than calcitic in its basic chemistry consistently proved to be more durable in weathering performance over time. The paper describes the process followed by the authors to categorize and study the distinct varieties of Georgia marble present on the Minnesota State Capitol, and how this information was used to guide the restoration process with the intent of maximizing the anticipated service life of new marble replacements.

A joint probability analysis of storm tides is made for the Battery, New York (U.S.A.), and Newark Bay, New Jersey (U.S.A.). Storm tides are caused by either low-pressure coastal storms (northeasters) or hurricanes. The analysis uses existing gage data at the Battery to construct frequency/probability curves of peak surge elevations and tidal amplitudes. These are used in a computer program to combine standard storm surge stages and tidal stage curves to produce an artificial storm tide with given peak elevation and incremental frequency. These peak elevations and incremental frequencies are ranked to produce cumulative frequency curves for northeasters and hurricanes. A frequency curve is obtained for Newark Bay via correlation.