Chester K. Wentworth

TL;DR: In this paper, the problem of terminology in geology has been discussed and the need for greater uniformity of usage and hence much confusion has arisen due to the indiscriminate use of the terms both in the old and new senses.

TL;DR: In the course of field work at Baraboo, Wisconsin, in the summer of 1916, it occurred to me that by means of a suitably designed tumbling barrel an experimental study might be made of the abrasion of cobbles in stream transit.

TL;DR: In this paper, it was concluded that steep-walled, blunt-headed box canyons and the imposing cliffs or "palis" of various parts of the Hawaiian Islands have long attracted the attention of travelers, and in some instances faulting or other tectonic factors have been invoked to explain them.

Abstract: I was much interested in the paper on the "Volume, Shape, and Roundness of Rock Particles" by Hakon Wadell in a recent number of the Journal of Geology.' The paper contains a valuable discussion of the geometric properties mentioned in the title and contributes a number of useful definitions. Certain statements and assumptions in it, however, seem to me to be susceptible of more than one interpretation and are the basis of the following comments. The ratio of the surface area2 of a sphere of equivalent volume to the surface area of the particle in question, is defined as the degree of true sphericity, and is truly regarded as an important factor in the behavior of such a particle in suspension. It seems to me that the surface ratio stated, which reaches the maximum value of unity in a sphere, is only one of the unique geometrical properties of a sphere and cannot be regarded as the exclusive measure of true sphericity. I have listed elsewhere two other unique properties of spheres.3 These are constant curvature over the entire surface and constant diameters in all directions through a common center. Wadell discusses, moreover, a solid having "a maximum degree of roundness," but which is "not a sphere."4 Later he defines an index of roundness based on the curvature of corners as an additional measure of shape and thus further discriminates between sphericity and roundness. I believe that most geologists regard "sphericity" as a precise term, indicating exactly the shape of a sphere and possession of the properties of minimum surface area in relation to volume, of constant diameters through a common point, and of constant curvature over the whole surface in all directions. Degree of curvature is a measure of approach to this end-condition and can be measured in

TL;DR: The Koolau dome, forming the east half of the island of Oahu, is notably elongate, built about a linear rift zone in which numerous feeder dikes occur in a dike complex over 30 miles long.