The Baltic sea-level oscillations in the Atlantic and Subboreal periods are known from sedimentary records on slightly uplifting coasts in Denmark and southern Sweden (e.g., Berglund, 1971 ; Digerfeldt, 1975 ). The periodicity of those oscillations is in close correlation with recent data on climatic cycles with a periodicity of 1500, 1000, and 550 yr (e.g., Stuiver et al., 1995 ; Chapman and Shackleton, 2000 ). The effects of regional eustatic oscillations in the coastal area of the Southern Baltic are poorly known because of the slightly subsiding coast and the magnitude of barographic and storm surges, which are larger than those of eustatic oscillations. To solve these problems, sediment sequences on the western coasts of the Puck Lagoon (northwestern part of the Gulf of Gdańsk) were investigated. Recent vertical movements of Earth's crust are ∼0.0 to −0.5 mm/yr. According to 14 C datings, pollen and diatom analyses, the earliest marine influences occurred in the Middle Atlantic period, while at the end of the Atlantic period almost all of the area was occupied by brackish waters ( Kramarska et al., 1995 ; Uścinowicz and Miotk-Szpiganowicz, 2003 ). Several sediment cores were taken along the western coast of the Puck Lagoon. Ordinates of the collected cores were geodetically determined to ± 1 cm relative to the mean sea level. Peat, plant remains, and marine shells (64 samples) were dated using the classic 14 C and AMS (accelerator mass spectrometry) methods. The plot showing the altitude of peat and marine mollusk shells versus their radiocarbon age shows that during the Subboreal and Subatlantic periods water levels in the Puck Lagoon were as follows: 5 ka B.P.—2.8 m, 4 ka B.P.—1.8–1.9 m, 3 ka B.P.—1.3–1.4 m, 2 ka B.P.—0.8–0.9 m, and 1 ka B.P.—0.4–0.5 m b.s.l. The rises in sea level during the Subboreal and Subatlantic periods may have been cyclical and related to climatic oscillations. The periodicity of water-level changes was ca. 1000 yr and their amplitude was ∼0.3–0.5 m. This is also confirmed by pollen and diatom analyses.

L ittle has been published concerning the fossil Crustacea of eastern and southern United States. The United States Geological Survey and the United States National Museum have been gradually accumulating specimens, but the sum total is moderate. Crustacean remains, compared to molluscan, are scarce. The shells are thin, fragile, and easily destroyed, so that the remains consist largely of chelae or parts of chelae, as these are usually thicker than the carapace and other appendages. The number of species at hand is relatively small; more are known from the lower Cretaceous of Texas and the Midway of Alabama than elsewhere. In the Cretaceous the predominating genera of shrimp-like forms are Hophparia and Callianassa-, the former belongs to the family, Homaridae, best known from the common lobster; the latter is a burrowing shrimp of a type which persists at the present day to a limited extent but which in ancient times was noted for the great number of species and individuals. The largest crustacean here recorded occurs in the Comanche series of Texas, a Palaeastacus figured on Plates 3–5. Several species of the genus Linuparus of the family Palinuridae indicate the derivation of Recent L. trigonus of Japan. The three pagurids, or hermit crabs, are referred to genera now living. A prevailing genus of true crabs is Necrocarcinus, a Calappid which became extinct after the Eocene. Fairly abundant are the Gymnopleura or Raninidae, representatives of which still persist in the waters bordering the Coastal Plain. Notable is the presence of two isopods, Aegidae, rare among fossils.