Comparison of magnetic properties and petrography between dykes and lava flows from La Cienega, New Mexico and Thunder Bay area, Canada

Data on the evolution of geomagnetic paleointensity are crucial for understanding the geodynamo and Earth’s thermal history. Although basaltic flows are preferred for paleointensity experiments, quickly cooled mafic dykes have also been used. However, the paleointensity values obtained from the dykes are systematically lower than those from lava flows. This bias may originate from the difference in cooling histories and resultant magnetic mineralogies of extrusive and intrusive rocks. To explore this hypothesis, the magnetic mineralogy of two feeder dyke-lave flow systems, from Thunder Bay (Canada) and La Cienega (New-Mexico), has been studied using magnetic and microscopy methods. Within each system, the flow and dyke show different stages of deuteric oxidation of titanomagnetite, but the oxidation stages also differ between the two systems. It is concluded that the tested hypothesis is viable, but the relationships between the magnetic and mineralogical properties of flows and dykes are complex and need a further investigation.

Our Lives, Our Thoughts and Our Allegiance: New Immigrants and American Industry in 1914

Through comparative analysis of the immigrant labor forces at work in iron mining in northern Minnesota, coal mining in Illinois, and steel milling in the Calumet region of Chicago and Gary, this paper addresses the forms of social distance separating and marginalizing new immigrants from American society and trade unionism that existed in 1914, the year that marked the end point of mass immigration from Eastern and Southern Europe. The “new immigration” was a labor migration that congregated its subjects overwhelmingly in what were called "unskilled" or "semi-skilled" forms of labor. Skilled work was largely, with certain variations, the preserve of "American" or old immigrant workers. This labor gulf separating new immigrants and American workers was hardened by a spatial separateness. New immigrants often lived in what have been called industrial villages—the mining town or location, the factory neighborhood— striking in their isolation and insularity from mainstream society. This separateness and insularity became a major preoccupation for corporate managers, Progressive reformers, and for American trade unions as new immigrants began to engage in major labor struggles leading up to 1914. But among the three industries, only the union of coal miners, the United Mine Workers, enjoyed success in organizing the new immigrants. In the steel mills and the iron mines, the unions were either rooted out or failed to gain a foothold at all. The explanation for these differences is to be found in the different forms of industrial development among the industries studied.