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Minor floods of 1938 in the North Atlantic States

Five noteworthy floods occurred during 1938 in the North Atlantic States. The first flood was in January, the others were in June, July, August, and September. The floods of January, June, and August were relatively local events in Connecticut, New Jersey, and New York, respectively. The floods of July and September were widespread, reaching from New Jersey and New York to New Hampshire in generally coincident locations. The flood of September, the most severe, is described in appropriate detail in Water-Supply Paper 867; the others in this volume are in separate sections arranged chronologically. Extraordinary floods in Connecticut during January 1938 resulted from a critical combination of warm rainfall and virtual overnight melting of the accumulated snowfall of winter. Seven small streams in central and western Connecticut rose to levels on January 25 higher than those reached during the great floods of March 1936. Crest discharge of these streams approximated 100 second-feet per square mile. Ice cover was loosened and sent downstream in recurrent jams. In general, the larger rivers did not attain extraordinary stages. The Connecticut River at Hartford peaked at a stage 3.6 feet above ordinary flood level. Direct damage by the flood was relatively small. Snow cover on January 20, at the beginning of the rains, varied from 0.25 inch along the coast to 2.75 inches water equivalent in the northern part of the State. Precipitation between January 24 and 26 exceeded 2.75 inches in only three small areas. Total supply as water in snow and precipitation did not exceed 4.8 inches over any tributary area. Maximum measured flood run-off was 2.7 inches. The flood of June 1938 in New Jersey was the immediate result of a 30-hour rainstorm on June 26-27 that centered along a line extending from Odessa, Del., to Milton, N. J. Storm rainfall exceeded 5 inches over a total area of 2,900 square miles. River stages in the central parts of the storm area rose to levels that approached and on a few rivers exceeded previous maxima of record. Damage was extensive throughout the storm area, especially in Burlington, N. J., where Sylvan Lake Dam failed. The highest rate of flow per unit of area measured was 88 second-feet per square mile. However, all peak discharges were exceeded during the later floods of 1938 or by the flood of September 1, 1940, which produced discharges over 1,000 second-feet per square mile in southern New Jersey. The maximum volume of direct runoff during the flood, expressed in mean depth in inches on the drainage area, was 2.1 inches. From July 17 to 25, 1938, there was an irregular series of rainstorms over the eastern seaboard that brought more than 10 inches of rain over an area of 2,000 square miles and more than 6 inches over 23,000 square miles. Nearly 14 inches of rain fell at Long Branch, N. J. Extraordinary floods occurred mainly in the smaller tributary streams. Damage to highways, homes, factories, and crops, particularly the tobacco co-op in Connecticut, was extensive. Crest discharges at 12 gaging stations exceeded those previously observed. Maximum rates of discharge varied from 601 second-feet per square mile for an area of 2.91 square miles in New Jersey to 35 second-feet per square mile for an area of 711 square miles in Connecticut. Antecedent soil moisture prior to the storm was probably normal or a little above. The maximum volume of direct runoff was 4.75 inches in Massachusetts, 5.6 inches in eastern Connecticut, 6.75 inches in the Catskill Mountain region of New York, and 4.95 inches in the Raritan River Basin of New Jersey. Infiltration indices from 0.09 .to 0.21 inch per hour were computed, such rates being within the range defined for basins in the same areas during the floods of September 1938. The flood of August 6-11, 1938, in the Catskill Mountain region of New York resulted from heavy rains with a maximum of 8 inches at two centers. Rainfall exceeded 3 inches over more than 3,000

Water Supply Paper↗

Sediments, structural framework, petroleum potential, environmental conditions, and operational considerations of the United States North Atlantic Outer Continental Shelf

The area designated for possible oil and gas lease sale as modified from BLM memorandum 3310 #42 (722) and referred to therein as the North Atlantic Outer Continental Shelf (OCS) contains about 58,300 sq km of shelf beneath water depths of less than 200 m and lies chiefly within the Georges Bank basin. The oldest sediments drilled or dredged on the bordering Continental Slope are sandstone, clay, and silt of Upper Cretaceous age. In Upper Cretaceous exposures, on Marthas Vineyard and nearby New England islands, the predominant lithology appears to be clay. About 125 km northeast of the eastern tip of Georges Bank, the Shell B-93 well penetrated clays and silts of Upper and Lower Cretaceous age above dense Jurassic carbonate rocks which overlie a basement of lower Paleozoic slate, schist, quartzite, and granite. Structurally, the Georges Bank basin is a westerly trending trough which opens to the west-southwest. Post-Paleozoic sediments are more than 8 km thick in parts of the basin. Major structural features appear to be directly related to basement structures. Local anticlines, probably caused by differential compaction over basement flexures and horst blocks or by later uplift along basement faults are reflected principally in Lower Cretaceous and older sediments, though some of these features continue upward to within 0.7 of a second (about 650 m) of the seafloor. Tertiary deposits in the Georges Bank basin are probably up to a kilometre thick and are made up of poorly consolidated sand, silt, and clay. The Cretaceous section is inferred to be up to 3.5 km thick and to be mainly clastics -- shale, siltstone, calcareous shale, changing to limestone in the lowest part of the system. Jurassic rocks in the deepest part of the basin appear to be about 3.6 to 4.0 km thick and probably consist mainly of dense carbonates. Potential source rocks in the Georges Bank basin may include organic-rich Cretaceous shale and carbonaceous Jurassic limestone. By analogy with the Scotian Shelf, Cretaceous sandstones are considered to be potential reservoir rocks. Local zones of porous dolomite are believed to be present in carbonate rocks of Jurassic age and should not be overlooked as potential reservoirs. Structural highs related to draping and differential compaction over basement blocks could be important potential petroleum traps. Additional traps may include reef structures near the shelf edge, updip pinchouts, and stratigraphic traps in both clastic and carbonate sediment. A statistical mean for the undiscovered recoverable petroleum resources is calculated to be 0.9 billion barrels of oil and 4.2 trillion cubic feet of gas. At the 5 percent probability level (1 in 20 chance) the undiscovered recoverable petroleum resources are calculated to be 2.4 billion barrels of oil and 12.5 trillion cubic feet of gas. These undiscovered recoverable petroleum resources are those quantities of oil and gas that may be reasonably expected to exist in favorable settings, but which have not yet been identified by drilling. Such estimates, therefore, carry a high degree of uncertainty. Environmental studies of Georges Bank indicated a low-moderate risk from petroleum development. However, the risk estimate is based on very limited data. Drift bottle returns used to infer oil spill trajectories show about a 2% overall recovery rate. Meteorologic data comes mainly from nearby land areas and from ships attempting to avoid storms. Seismicity on Georges Bank is low. This may reflect, in large part, the difficulty of land-based stations in recording earthquakes far from the coast. Direct data on the engineering properties of shallow buried sediment comes mainly from two Texas Tower surveys of limited areas on Georges Shoal and Nantucket Shoals made in the early 1950's. The 17 holes (most less than 30 m deep) reveal some silty layers below loose sand and much lateral variability in sediment type over short distances. The technology for exploration at the required water depths (20 m - 200 m) is available. Mobil drilling units are in great demand around the world and will have to be brought in from other areas along with skilled manpower. Our highest estimates indicate 50 platforms, 800 producing wells, 1,100 km of pipeline, and 5 onshore terminals may be needed. The time frame for production, using our high estimates (5% probability) for the undiscovered recoverable resources, could include 4-5 years for significant development, 6-7 years until production commences, and 18 years until peak production.

Open-File Report↗