Capturing the Center

Again, Lavoisier's insights are subtle and detailed--and several specific predictions can be made from his model. For example, the upper and lower littoral beds will be confluent near the coast because the intervening pelagic bed didn't reach this far inland. Thus, a vertical section drawn here should show a single thick littoral bed made of large and angular pebbles. But, farther away from shore, a vertical section should include a full array of alternating beds, illustrating the entire cycle and moving (top to bottom as shown in the vertical line, located just left of center and marked 12345) from the upper littoral bed of the falling sea (1) to the intervening pelagic bed (2), the lower littoral bed of the rising sea (3), the underlying chalk (4), and finally the foundation of the ancienne terre (5).

Thus, Lavoisier's model makes highly specific predictions about the sediments deposited in full cycles of rising and falling seas, as expressed in the vertical sections that adorned the right-hand margins of the maps he made with Guettard, and that represented his signal and original contribution to the developing science of geology. Moreover, the model specified predictions not only for the vertical sequences of single places but also for geographical variation in those sequences from place to place. Therefore, in a last figure, Lavoisier presents some actual vertical sections measured in the field. The example presented here corresponds exactly to his prediction for section 12345 in the idealized model. Note the perfect correspondence between Lavoisier's Coupe des Montagnes des Environ de Saint Gohain, "section through the mountains in the neighborhood of St. Gobain," and his model (except that the actual section doesn't extend below the chalk into the ancient basement). The measured section shows four layers, labeled upper littoral, pelagic beds, lower littoral, and chalk (note the layers of flint nodules in the lowermost chalk). Lavoisier had intended to write several more geological papers filled with similar empirical details to test his model. Thus, this pilot study presents only a few actual sections, but with impressive promise for validation. Lavoisier had achieved a scientific innovation of the finest and most indubitable form: he had added a dimension (literally) to our knowledge of natural history.

As if he had not done enough already, Lavoisier then ended his treatise with two pages of admittedly hypothetical reasoning on the second great general theme in the study of time and history. His model of oscillating seas lies fully within the Newtonian tradition of complete and a historical generality. Lavoisier's ocean cycles operate through time, but they do not express history because no events of distinctive directionality ever occur; no result ever denotes a unique moment. The cycles obey a timeless law of nature and proceed in the same way, no matter when they run; cycle 100 will yield the same results as cycle 1, and the record of rocks can never tell you where you stand in the flow of history. All variation reflects either general environment (high or low sea) or local circumstance (type of rock in the cliff being eroded), and not any distinctive imprint of history.