Geology topics
James Joyce
Publications and source records attributed to James Joyce.
The northwest trending north Boquerón Bay-Punta Montalva Fault Zone; A through going active fault system in southwestern Puerto Rico
The North Boquerón Bay–Punta Montalva fault zone has been mapped crossing the Lajas Valley in southwest Puerto Rico. Identification of the fault was based upon detailed analysis of geophysical data, satellite images, and field mapping. The fault zone consists of a series of Cretaceous bedrock faults that reactivated and deformed Miocene limestone and Quaternary alluvial fan sediments. The fault zone is seismically active (local magnitude greater than 5.0) with numerous locally felt earthquakes. Focal mechanism solutions suggest strain partitioning with predominantly east–west left-lateral displacements with small normal faults striking mostly toward the northeast. Northeast-trending fractures and normal faults can be found in intermittent streams that cut through the Quaternary alluvial fan deposits along the southern margin of the Lajas Valley, an east–west-trending 30-km-long fault-controlled depression. Areas of preferred erosion within the alluvial fan trend toward the west-northwest parallel to the onland projection of the North Boquerón Bay fault. The North Boquerón Bay fault aligns with the Punta Montalva fault southeast of the Lajas Valley. Both faults show strong southward tilting of Miocene strata. On the western end, the Northern Boquerón Bay fault is covered with flat-lying Holocene sediments, whereas at the southern end the Punta Montalva fault shows left-lateral displacement of stream drainage on the order of a few hundred meters.
Altitude and configuration of the potentiometric surface in the crystalline and metasedimentary rocks in Birmingham, Newlin, Pennsbury, and Pocopson Townships and parts of East Marlborough and Kennett Townships, Chester County, Pennsylvania, June 1994 through November 1995
A map showing ground-water levels in crystalline and metasedimentary rocks in Birmingham, Newlin, Pennsbury, and Pocopson Townships and parts of East Marlborough and Kennett Townships, Chester County, Pennsylvania, was constructed from water levels measured in wells from June 1994 through November 1995. Pre-1994 measurements were incorporated on the map to provide control in areas where more recent data were not available. Because little ground-water development has occurred in the areas where pre-1994 water levels were used, levels are assumed to be the same in 1994 and 1995 as they were when the measurement was made.