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This paper presents four terrain diagrams, on a scale of 1:1,000,000, which cover all the Philippine Islands. The diagrams were prepared during World War II by the Military Geology Unit of the U. S. Geological Survey for the Chief of Engineers, U. S. Army. Terrain features shown on the diagrams owe their individuality to the nature of the rock formations and the tectonics. Mountain areas are made

Second vertical derivatives of magnetic fields, because of their high resolving power, are often very useful in interpreting magnetic anomalies. Formulas are developed which permit their ready numerical computation. Comparisons are made between the resulting approximate values and the rigorous values obtained for simple idealized fields. The similarity between maps of second vertical derivatives o

The lavas of the Hawaiian Islands range from mafic picrite-basalts and melilite-nepheline basalts to salic trachytes. Olivine basalt, by far the most abundant type, is regarded as representing the parent magma of the Hawaiian province. Closely associated with the olivine basalts are basalts, and picrite-basalts with many large phenocrysts of olivine. Further differentiation results in eruption of

The gradational interrelationship of coal with cannel, boghead, torbanite, and oil shale is reemphasized in view of contrary opinions expressed recently. An example from South Africa that has recently been studied in some detail is cited in illustration of how closely coal and torbanite may be related. The scientific classification of the carbonaceous rocks requires a broader basis of comparison t

In the Azapa valley, Chile, Pleistocene and Recent alluvial fill, composed of intercalated lenses of clay, silt, sand, and gravel, contains a zone of saturation that is sustained by infiltration from floods of the San Jose river, from December through March.

Broad paleostructural development in south-central Pennsylvania and Maryland was similar to that of central and eastern New York during the deposition of lower Middle Ordovician beds. Thick marine limestones of the easternmost belts of outcrop in the Cumberland Valley indicate the southward extension of the Champlain miogeosyncline. Thin and, in part, coarse-textured limestones in belts of outcrop

An inventory of geologic mapping in the continental United States shows the areal extent of published geologic maps, differentiated by scales, and gives the results of calculations of the approximate number of square miles geologically mapped in each State on several scales, with separate figures for the maps published since 1919. Several graphs compare the progress of geologic mapping in the diff

Flood data are ordinarily listed either in annual‐flood series or in a partial‐duration series. If the expectancy of a flood in the duration series ϵ is known, then the probability of that flood being an annual flood is shown to be e−ϵ. From this relationship it is possible to transform recurrence intervals in the partial duration series to those in the annual‐flood series. It is shown that for eq

Two types of cleavage, schistosity (flow cleavage) and slip cleavage, are common in the metamorphosed sediments of east‐central Vermont. Two generations of cleavage are also recognized. Cleavage of the earlier stage of deformation is schistosity, and is generally parallel to bedding. Just west of the Monroe Fault, along the eastern border of the area, only this earlier schistosity is present; fart

The City of Bountiful, Utah, is situated just beyond the eastern edge of an area where alluvial gravel and sand of Pleistocene and probably Tertiary age yield water by artesian flow. Attempts to recharge these aquifers by diversion of surplus stream water into a spreading canal east of the city have been unsuccessful, because of the relative impermeability of the torrential debris which has accumu

As a basis to study the discharge characteristics of the Metolius River the John Day River was used. The Deschutes Basin of which the Metolius drainage area is a part was compared to the John Day Basin. There are several factors which must be considered when comparing the two basins. Perhaps the most important point which was not stresses is the fact that although about three‐fourths of the flow o