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Multiple subsamples of pollen samples obtained from the modern soil surface at two sites in southern Arizona were individually collected and analyzed to evaluate the practice of mixing subsamples when collecting modern surface samples. Results suggest that at least five subsamples must be mixed in order to avoid collecting a sample that is not representative of the local pollen rain.
A 2,500-yr pollen record from an alpine meadow in the central Sierra Nevada shows a general agreement with other more detailed pollen records from the late Holocene of California. Tree roots from the site suggest dry conditions at about 1150 and 1350 radiocarbon yr B.P.
Rb-Sr dating of Precambrian W (lower Precambrian) gneisses and granitic rocks that form the cores of antiforms or domes mantled by metamorphosed Precambrian X (middle Precambrian) bedded rocks in the Marenisco-Watersmeet area, northern Michigan, shows that the rock systems have been disturbed to different degrees by complex tectonic and thermal events subsequent to primary crystallization. The disturbance is indicated by a lowering of the whole-rock Rb-Sr ages of many samples of gneiss from 2,600 m.y. or older to about 1,800 m.y. and by the scattering of data points, although some of the points can be fit to secondary isochrons; probably the major mechanism was redistribution of previously accumulated radiogenic Sr, which is indicated by the high initial 87 Sr/ 86 Sr of the resultant isochrons. The disturbance is interpreted as having resulted from internal cataclasis and recrystallization accompanied by metamorphic segregation and (or) partial melting during reactivation of the gneisses about 1,800 m.y. ago. Variations in the degree of reconstitution and mobility of individual bodies of basement rocks are indicated by differences in structural reconstitution of the basement rocks and in the metamorphic grade of the Precambrian X bedded rocks.
Uranium and lead isotopic analyses of monazlte and uraninite from the disseminated uraninite occurrence at Wheeler Basin, Grand County, Colo., indicate that these minerals formed 1,446±20 m.y. ago. This time correlates well with intrusion of the Silver Plume Granite. The uraninite and monazite were also affected by a later disturbance at 880±130 m.y., but show essentially no effects of subsequent events. This secondary disturbance may have been due to intrusion of dikes related to the Pikes Peak batholith, dated at 1,041±13 m.y. ago.
Use of an iodide-ion-selective electrode permits rapid and fairly accurate determination of iodine (as iodide) in rocks and soils. When a 1-g sample is used, concentrations as small as 0.5 ppm can be determined with a precision of about 25-percent relative standard deviation. When bromine concentration is greater than 5 ppm, the same method can be used for bromine determination. The procedure merits further investigation as a possible tool in geochemical prospecting.
Fission-track ages have been determined on apatite and sphene from granitic rocks of the Salinian block, California Coast Ranges. The 26 age determinations on sphene range between 68 and 93 m.y. The 24 age determinations on apatite have a greater variation, ranging from 3 to 74 m.y. None of the fission-track ages appear to reflect times of intrusion. The Pinnacles volcanic field of Miocene age apparently has thermally affected apatite ages in the central Gabilan and eastern Santa Lucia Ranges. Reduced apatite ages in the area between the Farallon Islands and the Monterey Peninsula may also be the result of Miocene volcanic activity, but the evidence is less conclusive. Fission-track ages on sphene correlate closely with previously determined potassium-argon ages on hornblende and biotite but show an unexplained "bimodal" age distribution, the ages in the Gabilan and Santa Lucia Ranges being slightly, but consistently, lower (avg 75 m.y.) than the ages for terrane to the north and south (avg 85 m.y.) The overall pattern of the sphene and apatite fission-track ages, distinctly different from that of the central Sierra Nevada, may be a "fingerprint" of correlative value in locating the parent terrane of the "ripped-off" Salinian block.
As tributary streams in the Susquehanna River basin leave narrow upland valleys and enter larger valleys floored with permeable stratified glacial drift, they lose water by infiltration through streambeds. The infiltration rate is generally slow near the point of entering a larger valley, but farther downstream it is much faster and is approximately constant per unit distance along a given stream. A conservative average value of infiltration rate in the downstream reach is 10 liters per second per 100 meters of channel. Infiltration from these streams is little influenced by stream width, depth, or temperature and seems to be controlled by permeability distribution beyond the streambed in the alluvium or underlying glacial drift rather than by permeability at the streambed. Hydraulic conductivity of earth materials near each of the streams studied was calculated by applying models that describe steady-state saturated flow into isotropic materials with various boundary conditions. Hydraulic conductivities of 4 to 41 meters per day were obtained; 13 meters per day is suggested as a conservative average value for silty gravel alluvium in the Susquehanna River basin.
Morphologic and stratigraphic evidence bearing on the phylogenetic relationships of aulate Carboniferous corals suggests that species previously assigned to the genus Aulina Smith represent at least six different lineages that descended from three different ancestral genera. A classification designed to better reflect phylogenetic relationships includes the new genera Aulokoninckophyllum , Aulostylus , Solenodendron , and Vesiculotubus . The new North American taxa Aulostylus tubiferus tubiferus , A . tubiferus eotubiferus , and A . bamberi are described and illustrated. Two new Chinese species, Aulina ( Pseudoaulina ) loi and A . ( P .) sinensis , are also proposed.
The identification of plants and plant assemblages that are common to stream reaches that gain water and those that do not is an important key in the study of limestone hydrology. In the Ozark Mountains of Missouri, a rapid change from a stream-channel growth of abundant willows ( Salix spp.), touch-me-nots ( Impatiens capensis ), and sedges such as Carex Frankii and Eleocharis spp. to an abundant growth of bluestars ( Amsonia illustris ) indicates a rapid increase in depth to water. Vegetative indicators of hydrologic conditions are most helpful when used in conjunction with other information, but they are independently useful in pinpointing areas of abrupt hydrologic changes.
New molluscan assemblages of provincial early Miocene age from a previously unrecognized fossiliferous interval of 400 to 500 metres in the uppermost part of the Twin River Formation, western Washington, are referable to the upper part of the "Blakeley" [or Matlockian] Stage. The new biostratigraphic data provide, for the first time, definition of the uppermost part of the "Blakeley" Stage and the boundary between it and an unnamed stage of late early Miocene age represented by the Clallam Formation and its megafauna. In contradistinction to earlier studies, the upper boundary of the "Blakeley" Stage does not coincide with the upper boundary of the Zemorrian Stage of the foraminiferal chronology, the "Blakeley" boundary being at least 45 m higher and possibly much more. Nearly 60 species of mollusks from the upper few hundred metres of the Twin River Formation are recognized herein, and 40 of these are illustrated. Six species are previously undescribed.
High dissolved-iron concentrations have been noted in water in wells used to monitor effluent that percolates from wastewater disposal lagoons near Old Faithful in Yellowstone National Park. The concentration of dissolved iron in water in a well increased from 80 μ g/L (micrograms per liter) before a nearby lagoon was .used for disposal of effluent to 17000 μ g/L after the lagoon was used. The effluent contained 180 μ g/L of dissolved iron, and nearby Iron Spring Creek contained 30 μ g/L or less of dissolved iron above and below the lagoons. Organic carbon, nitrogen, and sulfur in the effluent as methane, ammonia, and hydrogen sulfide are oxidized to carbon dioxide, nitrate, and sulfate, respectively, in the unsaturated zone and possibly in the saturated zone as ground water moves through sand and gravel toward Iron Spring Creek. This oxidation results in simultaneous reduction of iron in the sand and gravel from the insoluble ferric phase to the soluble ferrous phase. As ground water high in dissolved iron discharges at land surface near the stream, oxygen from the atmosphere oxidizes the iron back to the insoluble ferric phase, and ferric hydroxide precipitates. Ferric hydroxide also precipitates in some of the monitoring wells. Iron bacteria and other organisms are associated with the precipitates.
Regional linear carbonate shelf margins, or stratigraphic reefs, are postulated to have developed during Mississippian time along the eastern flank of the Cordilleran miogeosyncline in the Western United States. These shelf margins are analogous to well-documented ancient and modern geologic counterparts, such as the Guadalupian reef of the West Texas Permian basin, the Lower Cretaceous Edwards shelf margin of the Gulf Coast, and the modern Florida reef tract-Straits of Florida province. Two Mississippian shelf margins are believed to have existed: The lower one developed as an integral part of a widespread carbonate depositional complex of Kinderhookian through early Meramecian age; the upper shelf margin developed west of the earlier stratigraphic reef as part of a regional carbonate depositional complex of middle Meramecian to late Chesterian age. Evidence for both shelf margins consists of (1) a linear physical barrier, (2) restricted sediments in the shelf interior, (3) abrupt basinward thinning of sediments and basin-starvation just seaward of the shelf edge, (4) profound fades-changes coincident with the basinward thinning from light-colored, skeletal, shelf carbonate rocks to dark, fine-grained, silty, basinal carbonate rocks, and (5) the consistent regional occurrence of the first four patterns. Seaward topographic relief along the front edge of the lower shelf margin was probably about 200-400 m, and maximum relief along the central sector of the upper shelf margin may have approached 1,000 m.
The coagulating ability of partly neutralized AlCl 3 solutions used in water treatment depends on their basicity, expressed here as the ratio NaOH/AlC 3 . This work presents an identification of the aluminum species active in the coagulation process. The results give rise to an interpretative model which is consistent with those models proposed for high ionic strength by other investigators.
New paleontologic evidence requires a revision of previous interpretations of the stratigraphy of Mississippian sequences in the Cordilleran miogeosyncline of eastern Idaho and northeastern Utah. A postulated unconformity between rocks of early Osagean age and rocks of middle Meramecian age is no longer tenable in the light of new data. The new evidence supports continuous deposition from the Lodgepole Limestone (Kinderhookian and early Osagean age) into the Little Flat Formation (early Osagean to middle Meramecian age) and its equivalents, and the interpretation of a phosphatic siltstone and shale interval in the lower part of the Little Flat Formation as a starved-basin facies.
Results of forest-trend modeling from one data set in the Atchafalaya River basin show that predicted forest acreage totals for 16 forest types agree within 30 percent of actual values in two-thirds of the comparisons. A forest-trend simulation model based on statistical regression relations of forest and hydrologic variables and constrained by forest succession concepts was developed using observed data from twenty-four 8-square-mile (20.74-square-kilometre) quadrats. Forest and hydrologic data at each quadrat were sampled in time at three 4-mile (6.44-kilometre)-wide strips across the basin. The model predicts changes in forest-type acreages due to hydrologic change in time steps, or forest acreage transition, of 21 years. Further basin-wide quadrat simulations are planned using hydrologic input data from a flow-sediment model of the basin currently being developed. Other ecosystem models could be appended to the forest-trend simulation model.
Two trenches were excavated across the 1906 trace of the San Andreas fault near fences that were displaced by the 1906 faulting. About 18 displacements equal to the 1906 displacement would account for the offset of a stream adjacent to one of the trenches. Review of divergent reports on the amount of fault displacement in 1906 at 7 localities indicates that right slip ranged from about 2 in (meters) to about 3 m at the main trace and was about 0.6 m on a subsidiary trace near one of the trench sites. Materials exposed in the trenches included Franciscan bedrock, Merced (?) sandstone, alluvial deposits, and modern soils. Visibility of the evidence for faulting covered a wide range. Faulting was expressed in the trenches as conspicuous color differences, abrupt termination of geologic units, fractures, gouge, granulation of rock, streaked contacts, rounding of rock fragments, and slickensides. Irregularly shaped masses of gouge and other materials found in both trenches may also be a manifestation of faulting. Neither caving of the walls nor the inflow of ground water were reliable indicators of the locations of faults in these trenches. The features exposed in the trenches clearly indicated the presence of an important zone of faults with geologically young displacements, but they were inadequate to identify with certainty the 1906 break or the probable 1838 break. For example, evidence of the 1906 rupture could not be seen in a unit 200 mm (millimeters) thick that is believed to predate 1906. The approximate location in the trenches of the 1906 zone of ruptures could, however, be inferred from surface morphology, historic records, and evidence in the trenches. A moderately sharp and steep contact between two surface soils, in itself suggestive of very young faulting, did not have a fault below it. Brass monuments were installed at the trench sites so that future surface ruptures can be related to the faults and other structures mapped in the trenches.
A 1-day reconnaissance of the Dietrich River, Alaska, included collection of benthic invertebrates. Three methods were used at each of five stations to increase sampling effectiveness and to evaluate each method. Chironomidae and Plecoptera comprised 91 percent of all individuals and 47 percent of all taxa in the combined faunal list. At each station, the most abundant organisms were taken by all methods but the less abundant ones by only one or two methods. The dip net collected the highest percentage of taxa, and the second highest percentage of individuals. The 10-rock method collected the highest percentage of individuals but was relatively ineffective for taxa. The drift net collected the fewest individuals, but the percentage of taxa was relatively high. Of the 27 unique taxa (those taxa collected by only one of the methods), 15 were collected by dip net, 8 by drift net, and 4 by the 10-rock method. The methods differed in their effectiveness with regard to collecting the most abundant taxonomic groups. Although the dip net was most effective for collecting taxa, more thorough scrubbing of substrates to remove clinging organisms probably would improve the technique.
Remnants of old alluvium on bedrock benches, as much as 76 in (250 ft) above the present course of the Cumberland River near Flat Lick, Ky., are associated with meander scars and broad valleys now occupied by underflt streams. The distribution of old alluvium and associated topographic features define two ancestral channels of the Cumberland River. The ancestral channels and the present river channel are superimposed on the crest and flanks of the Flat Lick anticline. All three channels trend westward, roughly parallel to the axis of the anticline. The oldest channel is on the north flank, the second oldest channel is superimposed on the crest, and the modern channel is entrenched in the south-dipping limb of the fold. The sequential pattern of channel downcutting and migration across the crest of the anticline can be explained in terms of structural and lithologic constraints upon fluvial processes without recourse to contemporaneous tectonism. The Flat Lick area apparently has not experienced major deformation during the erosional history interpreted from the surficial geology. Direct evidence for the age of the old alluvium has not been found. However, an estimate based on erosion rates suggests that the ancestral channels could have been established and abandoned as recently as one-half million years ago.