Intertidal zonation, observed from earliest studies of the marine littoral zone, was first studied in the U.S. by ecologists with a botanical orientation. Using the physiological methods favored by Cowles, Clements, and Shelford, these early studies sought causal and deterministic explanations. By the 1930s, the limitations of these studies became apparent and ecologists returned to more descriptive approaches. With the creation of year round research laboratories on the west coast, ecologists soon shed the botanical orientation and began to adopt more stochastic and non-deterministic approaches to intertidal ecology, approaches that still characterize the research tradition.