ASSOCIATION R O U N D TABLl-: 473 of about 65 miles are reasonably documented, greater displacements of older rocks are presently speculative and require more precise substantiation. The late Eocene-to-Oligocene depositional histories of the southern San Joaquin Valley, east of the fault, and the Santa Cruz Mountain region, west of the fault, are symptomatic of a genetic relation. The upper Tejon, San Emigdio, Pleito, and lower Temblor Formations of the San Joaquin Valley are believed to be homologous with the San Lorenzo, Vaqueros, and lower Hester Formations of the Santa Cruz Mountains. No comparable sequence of rocks is known from intervening areas adjacent to the San Andreas fault; therefore post-Oligocene movement? of about 225 miles are confirmed. The late Eocene-to-Oligocene foraminiferal lineage of Uvigerina jacksonensis <-> U. tiimeyensis ^-> "Siphogenerina" nodifera <-> "S." transversa occurs in both regions and corroborates the age relations of the for mations. somewhat less diver.-^c and abundant biota than the Kalkberg. The New S<olIand is interpreted as having developed on a broad shelf like the Kalkberg (and marginal to it), but with significantly greater influx of terrigenous detritus v\ hich probably came from a distant easterly source. Lateral and \erti<al \arialions in constituent carbonate-grain types, mudstone-sparite ratios, fossil abundance and diversity, and presence of primary sedimentary structures provide criteria for recognizing the transgressive natuie of the major sedimentary facies of the Helderberc Grou]j, The inferred depositional framework, moreover, is very similar to that postulated by Shaw (10(i4) and Irwin (196,T) for "clear water" sedimentation within an epeiric sea and demonstrates the predictive i-alidity of their general ized sedimentary model. LAPORTE, LEO F., Department of Geology, Brown University, Providence, R.L ECOLOGIC CRITERIA FHU RiaocNrnoN OF DEJ'OSITIOKAI. ENVIROXMENIS IN ('ARiiiiM.vrE ROCKS RECOGNITION OF TEANSGRESSIVE CARBONATE SKOUENCE W I T H I N EPEIRIC SEA: HELDERBEEG GKorp (LOWER DEVONIAN) OF N E W YORK STATE Carbonate skeletons nf njany Recent and fossil species show morphologic characters which can be related to specific factors in llieir environments. Similarly, the mineralogy and cheniislry ,ji the carbonate from the skeletons are known u, reileet a variety of ecologic factors. Few attempts have been made to utilize the ecologic information from the (ihysical and chemical proper ties of skeletal carbonates in tlie analyses of deposi tional environments of carbonate rocks. Data are presented lo ilhistrate their usefulness in recognizing certain ecoinnic: factors in the depositional environment of carbutiaic ii>cks. In this presentation, particular emphasis is |ilaced on comparative func tional morphologj' of carbonate skeletons. Ecologic factors to be i onsidered ,iro habitat, derivation of constituent grains, rales of sedimentation, turbidity, micro-hydrograpfiy. iiinsi~tenc> of the sediments, temperature, and (le|ill 'I (lie accumulating .sediments, The regional Late Silurian-Early Devonian marine transgression of the central Appalachians is represented in New York State by a shallow-water carbonate rock sequence (Helderberg Group) Vfhich locally transgressed north and west. The resultant stratigraphic section comprises several hundred feet of fossiliferous limestone which has several distinctive sedimentary facies. Early workers interpreted each of the major facies as a separate time-stratigraphic lithologic unit or formation. However, from detailed field examination Rickard (1962) demonstrated that these formations are in fact time-transgressive toward the west and interfinger laterally with each other. Paleoecological study of the Helderberg Group supports this interpretation and shows that each of the formations represents a local sub-environment within the transgressive interval as a whole. These formations (faciesi are: (1) Manlius Formation (25-50 feet), a complex of rock types interpreted to represent supratidal. intertidal, and shallow subtidal environments within a broad shelf lagoon (Laporte, 1964; 1967). (2) Coeymans Formation (20-100 feet), crinoidalbrachiopod skeletal calcarenite and carbonate siltstone which are commonly burrow-mottled toward the Isase of the unit but which show increasingly greater evidence of current reworking toward the top (high-and low-angle cross-stratification and sheet deposits). The Coeymans is interpreted to have been deposited in a wide belt of shallow, submerged crinoid mounds and banks which served as an effective, though discontinuous, barrier to circulation separating the more openmarine environment on the east from the jestricted shelf lagoon of the Manlius on the west (.Anderson, 1965). (3) Kalkberg Formation (50-100 feet), highly burrow-mottled carbonate mudstone with a very abundant, diverse, and well-preserved biota. The Kalkberg is interpreted to be a shallow-water, o[)enmarine deposit which developed on an extensive shelf seaward from the Coeymans crinoid banks and meadows. (4) New Scotland Formation (50-150 feet), highly argillaceous and siliceous carbonate mudstone with a LEDING1LA.M, G l . l N W ;see Frank! and C\)rdry] LOWENSTAM. H, .\.. California Institute of Teclinology, Pasadena, Calif. MARTIN, PALL S., tk-oclinmology Laboratories, University of Arizona, Tucson. Ariz. POLLEN STRATicR.wfiv OK I'I.WA LAKES Since the discover\ I "^ years ago by Sears and Clisby that the dry lakes ijilaya, lakes) of western North America contain a rich fossil pollen record, Pleistocene specialists have hoped that a definitive chronology would he forthcoming from this largely unglaciated region. Such a chronology ^l.oiild indicate the number of pluvial episodes and tl i magnitude of each. The deepest driU cores should leveal whether the Pleistocene began with a "bang" fiv a whimper." Though hopes for a rnntinuiiiis Pleistocene chronology go Uirgely unrealized, the (lollen record of the last glacio-pluvial maximum, tl r Wisconsin, is increasingly well known It indiiati'^ a inaior shift in vegetation zones not once bill -e\iial limes during the C14-datable part of iW leiurcl. Among the areas studied to date are the San .Au,!.»u3tin Plains, the Willcox Playa, Great Salt Lake Desert, and the Texas High Plains. Some rcmtiol on the fossil pollen record can be gained from lliC nicpdeni pollen rain of "natural" plant communities in I he southwest. Despite formidable problems of lon.^-ili>tance transport of certain pollen types it appear^ ||;a1 the major vegetation zones have thc'ir O\MI iliM M(1]\e local pollen pool,