Lewis reasoned that the north fork had to run an immence distance through the Plains to pick up enough sediment to make it so cloudy and turbid, whereas the south fork must come directly out of the mountains. The bed of the south fork was composed of smooth stones, “like most rivers issuing from a mountainous country,” and the bed of the north fork was mainly mud. He and Clark talked it over, without reaching a precipitate conclusion. “Thus have our cogitating faculties been busily employed all day,” Lewis wrote.
Most modern US military aren't this astute.
