Restoration of plate consumption recorded by Caribbean arc volcanism reveals probable plate movements that led to the emplacement of the proto–Caribbean plate into the present Caribbean region and provided the space necessary to accommodate the rotation of the Yucatán Peninsula concurrent with the opening of the Gulf of Mexico between ca. 170 Ma and 150 Ma. Fault movement of the Yucatán, caused by edge-driven processes, resulted in counterclockwise rotation, as shown by paleomagnetic studies. Restoration of Yucatán rotation necessitates the presence of a paleogeography different from the current distribution of the Greater and Lesser Antilles. During emplacement of the Caribbean plate region, four magmatic belts with distinct ages and different geochemical characteristics are recorded by exposures on islands of the Antilles. The belts distinguish the following segments of Cretaceous and Tertiary magmatic arcs: (1) an Early Cretaceous geochemically primitive island-arc tholeiite suite (PIA/IAT) typically containing distinctive dacite and rhyodacite that formed between Hauterivian and early Albian time (ca. 135–110 Ma); (2) after a hiatus at ca. 105 Ma of ∼10 m.y., a voluminous, more-extensive calc-alkaline magmatic suite, consisting mainly of basaltic andesite, andesite, and locally important dacite, developed beginning in the Cenomanian and continuing into the Campanian (ca. 95–70 Ma); (3) a second (calc-alkaline) suite, spatially restricted relative to the older belts, that consists of volcanic and intrusive rocks, which formed between the early Paleocene and the middle Eocene (ca. 60–45 Ma); and (4) a currently active calc-alkaline suite in the Lesser Antilles typically composed of a basalt-andesite-dacite series that began to develop in the Eocene (ca. 45 Ma). Plate convergence took place along northeastward- or eastward-trending axes during the formation of the Caribbean, which is outlined by the Antillean islands and Central and South America. Movements were facilitated by strike-slip faults, commonly trench-trench transforms, as subducting crust was consumed. Restoration of apparent displacements of at least several hundreds of thousands of kilometers along the inferred lateral faults of the Eocene and younger Cayman set separating Puerto Rico, Hispaniola, and the Oriente Province of southeastern Cuba brings together Eocene volcanic rocks revealing a magmatic domain along the paleo–south-southwestern margin of the Greater Antilles. The transforms along the southern margin of the Caribbean plate are mainly obscured by contractional deformation related to the northward motion of South America as it was thrust over the faulted plate margin. Restoration of the Caribbean plate also translates the Nicaragua Rise westward, thereby revealing a pathway along which Pacific oceanic lithosphere, mainly composed of a large, Late Cretaceous igneous province (Caribbean large igneous province), manifest as an oceanic plateau (Caribbean-Colombian oceanic plateau), converged toward and subducted beneath the southern flank of the Cretaceous Greater Antilles magmatic belt between 65 and 45 Ma. The Eocene arc rocks overlie or abut previously recognized Early and Late Cretaceous subduction-related units. Eocene consumption of Pacific lithosphere ceased with the arrival, collision, and accretion of buoyant lithosphere composed of Caribbean large igneous province. The Greater Antilles formed during Late Cretaceous subduction of Jurassic ocean crust beneath an Early Cretaceous arc formed at the eastern margin of the proto–Pacific plate. Formation of a volcanic edifice above Early Cretaceous arc rocks was followed by plate collision and coupling of the Greater Antilles belt against the Bahama Platform. The most straightforward path of the Greater Antilles into the Caribbean is along northeast-striking transforms, one of which coincided with the eastern margin of the Yucatán Peninsula. The transform appears to link the Motagua suture to the Pinar del Rio Province of western Cuba. To the southeast, the arc was transected by a second transform, perhaps coinciding with the present trace of the Romeral fault in northwestern South America and extending northeast to the eastern terminus of the Virgin Islands. During Late Cretaceous convergence, a segment of the extinct Early Cretaceous arc, developed at the Pacific margin, was carried northeastward.

Abstract Early studies stressed the high accretionary potential of Caribbean coral reefs (10-15 m/kyr). Cores from St. Croix (US Virgin Islands) suggested that the earliest reefs along the shelf edge were dominated by rapidly growing Acropora palmata. As the bank flooded, soil mobilized by wave action moved off the bank, killed these reefs, and prevented subsequent reef development for at least 2000 years. Because the shelf east of St. Croix is similar to many Caribbean sites, it was proposed that this model was widely applicable throughout the region. More recent data from cores and outcrops throughout the Caribbean show that reefs on St. Croix and elsewhere flourished throughout the hiatus originally proposed to have occurred between 10,000 and at least 8000 years ago. Furthermore, data compiled from all known Caribbean cores suggest that reefs built at rates averaging only 3.47 m/kyr and that reef-accretion rates above 7 m/kyr were exceedingly rare. The pattern of reef building and abandonment over the past 20,000 years is consistent with these findings. Reefs easily kept up with sea level when it was rising at rates below 3-5 m/kyr, and back-stepping consistently occurred throughout the intervening interval when sea level rose at rates up to 10 m/kyr. While sudden shifts in sea level have been well documented in the geologic record and degraded water quality will undoubtedly compromise reef building, triggers for back-stepping need not be confined to these scenarios. The mechanisms for back-stepping are complicated and still poorly understood. In virtually every well-documented case for the Holocene, neither community structure nor water depth over the abandoned reefs and their landward replacements were significantly different. Each new reef formed as sea level rose over an antecedent feature that favored reef formation, and its success was largely determined by the rate of sea-level rise at the time accretion began. Reefs that formed when sea level was rising faster than 3-4 m/kyr were eventually abandoned. The scale of these reefs and the magnitude of back-stepping are similar to many ancient examples. Assumptions that these reflect sudden shifts in sea level or severe environmental conditions should be reexamined in light of the realization that back-stepping can also be explained by physical and biological processes that are observable within the lifetime of a single reef scientist.

Abstract Marine environments include anything seaward of the shoreline, the dividing line between land and water. All environments can be considered as either terrestrial (on land), marine (under water), or transitional (transitional between land and water). The transition zone between terrestrial and marine environments includes such environments as tidal flats, estuaries, dunes, and beaches and barrier islands. Beach features and processes are covered in another chapter of this volume (Bush and Young, this volume). Part of the beach system also belongs to the nearshore zone, so it is impossible to completely disassociate the beach/ transitional zone from the nearshore marine system. Standard beach terminology delineating the environmental zones of the nearshore system is shown in Figure 1 . To define the limits of the beach and the limits of the nearshore marine system, begin with the above water part of the beach, the part landward of the shoreline. This is known as the backshore, but is also often referred to as the dry beach, the recreational beach, or the subaerial beach. Looking seaward, the shallowest part of the beach is the intertidal zone, the portion between high tide and low tide. This is also known as the foreshore. Seaward of the foreshore is the inshore, commonly called the shoreface, the deeper water extent of the beach system. The shoreface is the zone where waves approaching land first start to interact with the seafloor. Another way to look at it is that the shoreface is the seaward extent of sediment movement