Abstract

On Saturday afternoon March 30, 1996, the University of Michigan hockey team won the 1996 National Collegiate Athletic Association Division I national championship. Durations between Wolverine goals, between opponent goals, and between all goals during the preceding 40-game regular season each describe an exponential distribution in which duration frequency depends only on number of shots on goal and probability of success. Compared to opponent scores, University of Michigan between-goal duration frequencies describe a trend having a steeper slope (University of Michigan shot better) and a higher intercept (University of Michigan took more shots).

Over much of the past 100 yr, meteoric precipitation on Ann Arbor occurred during 11 949 days. Time durations of the 6401 precipitation episodes that occurred over this interval, as well as durations of contiguous days of precipitation and contiguous days of drought, each define an exponential distribution in which duration frequency is largely defined by total interval length (35 101 days) and probability of precipitation (34%).

Roadcuts near Wytheville, Virginia, provide spectacular exposures of a 303.7-m-thick section of peritidal carbonate in the Middle to Upper Cambrian Elbrook and Conococheague Formations. Stratigraphic durations (thicknesses) of the 527 lithologic units within this sequence, of the 265 “cyclic” upward-shallowing lithofacies associations that can be designated over this interval, and of stratigraphic intervals between recurrences of like lithofacies, also define exponential distributions wherein frequency of stratigraphic recurrence is only dependent on the total thickness and net abundance of designated stratal elements.

Frequency of goal scoring, and frequency and/or magnitude of meteoric precipitation can be described in terms of random, independent processes at short time scales. Similarly, exponential distributions of lithologic and “cyclic” thickness frequencies at Wytheville, Virginia (as well as in most other epicratonic peritidal sequences), indicate that meter-scale variation in carbonate deposition was predominantly controlled by stochastic (Poisson) processes that were largely unrelated to recurrent intrabasinal or extrabasinal forcing and/or to periodic (rhythmic) sediment accumulation.

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