In the first paper of this two-part series, Todd et al. (1982) pointed to evidence that the Stillwater Complex is the product of two parent liquids, the first having ultramafic characteristics, the second, anorthositic affinities. From their data, they argued that the J-M Reef sulfides formed from immiscible sulfide liquid precipitated in response to mixing of the two parents, with the Pt and Pd apparently being derived from the first and most of the sulfur from the second. The present paper is an attempt to describe the chemical and physical processes involved in the mixing event. Support for the analysis is drawn through comparisons with, and parallel applications to, the stratigraphically similar Bushveld Complex and its PtPd ore zone, the Merensky Reef.The analysis is based on evidence that the two Stillwater liquids differed sufficiently in density to form separate layers in the magma chamber and on the postulate that their crystallization and mixing were controlled by double-diffusive convection. As background, some of the characteristics of convecting liquid layers are described, with emphasis on the differences between (1) diffusive interfaces, as developed when a hot liquid underlies a relatively cooler but less dense liquid of different composition, and (2) finger interfaces, as formed when a relatively hot liquid floats on a cooler liquid that is denser only because it is cooler. Through the former, thermal and chemical exchanges ideally occur only by diffusion, and the interfaces tend to inhibit mechanical mixing of the liquids. By contrast, finger interfaces develop because the diffusive exchanges cause mechanical mixing.A new concept of the solidification of layered ultramafic-gabbroic intrusions is then described in which whole sequences of cumulates form concurrently by downdip accretion from a column of liquid layers that are primarily separated by diffusive interfaces. Each cumulate layer grows from one or more liquid layers, with the lower cumulates growing in advance of the upper cumulates in accord with their higher crystallization temperatures. If the liquid residua fractionated along the crystallization front have lower densities than their respective parent liquids, then they are continuously transferred, step by step, up the front. This transfer eventually eliminates each liquid layer that occupies the bottom of the column, but it also produces new layers at the top. Thus, the intermediate layers gradually subside in the magma chamber, and the cumulate strata, developing in growth pursuit of their respective parents, form inclined into the chamber with primary dips.In the absence of reliable compositions for the Stillwater ultramafic and anorthositic liquids, this concept is applied to the complex by way of a model system, Mg•SiO4-CaMgSi•O6-CaA12Si2Os-SiO2. Extensive use is made of a new type of liquidus diagram in which the products and densities of all liquids fractionated from a mixing line between two starting compositions can be compared conveniently. Model parent compositions are c...

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Ozark Bass (Ambloplites constellatus) is an understudied, endemic fish species in the Upper White River Basin of northern Arkansas. This study was part of an effort by fisheries managers to gather baseline data about the Ozark Bass to aid in understanding population dynamics and contribute to the limited data available for use in determining the efficacy of harvest regulations. Select population characteristics of Ozark Bass in two northern Arkansas streams were determined, population characteristics of Ozark Bass were compared to Shadow Bass (Ambloplites ariommus) and Rock Bass (Ambloplites rupestris) data collected from previous studies in southern Missouri, and relative condition, length-at-age, and annual survival of Ozark Bass were compared between sample streams. Sampling occurred in Crooked Creek and the Buffalo River during summer 2013 via boat electroshocking. Length and weight data were recorded for all Ozark Bass collected, and fish ages were determined through selective otolith retrieval and age-length keys. Ozark Bass in Crooked Creek had greater relative condition than Ozark Bass in Buffalo River (P < 0.001). Neither Ozark bass lengths nor log-transformed weights differed (P > 0.05) between sexes for fish collected from only the Buffalo River. Ozark Bass mean annual survival was similar between Crooked Creek (55% ± 5% as 95% confidence interval (CI)) and the Buffalo River (50% ± 7% CI) for fish age 2 to 9. Calculated Ozark Bass lengths-at-age for fish from both streams were comparable to the Von Bertalanffy growth estimates, except the Buffalo River age 7 category where there was only one observation. The relationship between Ozark Bass age and length differed between sam-How to cite this paper: