The geology of the Øvre Heimdalen valley

Øvre Heimdalsvatn is clearly influenced by the geological conditions, and the lake basin and catchment area are determined by the bedrock and the mountain structures. The distribution and characteristics of the loose deposits are decisive for the lake's water budget. The groundwater in the catchment area and the Quaternary deposits near the lake influence the amount and quality of the lake waters.     

The effect of habitat geology on calcium intake and calcium status of wild rodents

Summary Calcium is essential for normal physiological function, reproduction and growth in mammals but its distribution in the natural environment is heterogeneous. Spatial variation in calcium soil content is especially marked in the Peak District, United Kingdom, where both calcium-rich limestone and calcium-poor gritstone rock types occur. Wood mice Apodemus sylvaticus (L) and bank voles Clethrionomys glareolus (Schreber 1780) from limestone areas had significantly higher calcium concentrations in stomach contents and in faeces compared with their counterparts from gritstone areas. Calcium status was assessed from serum calcium concentration, femur weight, ash content of the body, calcium concentration in the femur and body ash. There was no significant difference in serum calcium concentration, femur calcium concentration and body ash calcium concentration between animals from the limestone and the gritstone. However, on the limestone, bank voles, but not wood mice, had significantly heavier femora and a greater proportion of ash in the body compared with their gritstone counterparts.     

Biology and geology of eastern Pacific coral reefs

Coral Reefs -  The tropical eastern Pacific region has historically been characterized as devoid of coral reefs. The physical conditions of the region are apparently not conducive to reef...     

Editor's column: Stratification in international geology

The two large organizations in international geology, the permanent International Union of Geological Sciences (IUGS) and the long-term International Geological Correlation Programme (IGCP), are strongly stratified units and victims of platform sedimentation. Their National Committees and corresponding bodies are often useless as channels of the active scientists' initiative and influence. Their constituent and affiliated scientific bodies are deprived of all influence on the management of the organizations, in favour of managements bureaucratically and autocratically recruited according to a pattern of equitable geographical distribution. The IGCP is wasting effort in hunting for programme gaps, whilst both organizations are campaigning against regional concentrations of interest and consequent influence. Both organizations are in bad need of activating their national members and opening up their management to influence from their scientific bodies. For this purpose important changes in their constitutions are needed. Only then can their formal strength become real and their many challenging tasks be efficiently tackled.     

The relationship between surface water chemistry and geology in the North Branch of the Moose River

The chemistry of lakes and streams within the North Branch of the Moose River is strongly correlated with the nature and distrubution of geologic materials in the watershed. The dominance of thin glacial till and granitic gneiss bedrock in the region north and east of Big Moose Lake results in a geologically sensitive terrain that is characterized by surface water with low alkalinity and chemical compositions only slightly modified from ambient precipitation. In contrast, extensive deposits of thick glacial till and stratified drift in the lower part of the system (e.g. Moss-Cascade valley) allow for much infiltration of precipitation to the groundwater system where weathering reactions increase alkalinity and significantly alter water chemistry.The hypothesis that surficial geology controls the chemistry of surface waters in the Adirondacks holds true for 70 percent of the Moose River watershed. Exceptions include the Windfall Pond subcatchment which is predominantly covered by thin till, yet has a high surface water alkalinity due to the presence of carbonate-bearing bedrock. The rapid reaction rates of carbonate minerals allow for complete acid neutralization to occur despite the short residence time of water moving through the system. Another important source of alkalinity in at least one of the subcatchments is sulfate reduction. This process appears to be most important in systems containing extensive peat deposits.An analysis of only those subcatchments controlled by the thickness of surficial sediments indicates that under current atmospheric loadings watersheds containing less than 3 percent thick surficial sediments will be acidic while those with up to 12 percent will be extremely sensitive to acidification and only those with over 50 percent will have a low sensitivity.     

The physical basis of the Lake Mikri Prespa systems: geology,climate, hydrology and water quality

Lake Mikri Prespa is 47 km² in area, with amaximum depth of 8.4 m and a normal water level ataround 850 m above sea level. It collects water froma granitic and karstic catchment of 189 km² whichincludes snowy mountains rising to over 2000 m. Themain flat land is the sedimentary plain to the eastand the sandy isthmus that separates Mikri Prespa fromthe much larger Megali Prespa into which the formernormally drains. Rainfall averages around 750 mmbecause the 600 mm to 700 mm falling on the plains isaugmented by heavier falls including much snow on themountains. There is rainfall each month with anautumnal maximum. River inputs to the lake and thelake level itself peak in the spring with thesnowmelt. Mikri Prespa normally rises by about a metreto flood the surrounding wet meadows landward of thereed fringe. The annual cycle of water levelfluctuation is superimposed on infrequent upwardsurges in the level of Mikri and Megali Prespa becauseof particularly wet and snowy winters and, in recentyears, the steady decline of the level of MegaliPrespa because of tectonic activity.There has been considerable human modification of thehydrology of the area with the diversion of the AgiosGermanos torrent from Mikri to Megali Prespa, thecreation of a canal in Albania which can input orwithdraw water from the lake, the culverting of thecanal linking Mikri and Megali Prespa, and thecreation of an irrigation scheme taking water directlyfrom Mikri Prespa and from the Agios Germanosstream.The lake water is base rich because of the limestonein the catchment. Whilst concern has been expressed atthe eutrophication of the lake, recent studies haveproved that there has been no significant change innutrient status this century and the lake is noteutrophic. There has been a significant increase inturbidity but this may be the result of sedimentdisturbance by an introduced fish species.The lake and its supporting hydrological system willneed careful monitoring if it is to be effectivelymanaged. A particularly high priority is thedevelopment and implementation of a water levelmanagement plan for the lake.     

Trophic status of Iowa Lakes in relation to origin and glacial geology

Natural and artificial lakes in the most recently glaciated portions of Iowa have significantly greater total ion concentrations than those in other areas of the state. A similar distribution was found for total nitrogen concentrations. Lake origin seems of greater importance than location in determining trophic state. As a group, the artificial lakes have lower concentrations of total phosphorus, total chlorophyll, and greater Secchi disk transparency than do the natural lakes. This seems related to differences in the dynamics of the phosphorus cycles in these lake types.     

The contribution of flood disturbance, catchment geology and land use to the habitat template of periphyton in stream ecosystems

1. Periphyton chlorophyll a (chl a), ash-free dry mass, taxonomic composition, and cellular and water-column nutrients were analysed every 4 weeks for a year at sixteen stream sites in New Zealand. The hypothesis was investigated that broad-scale differences in mean monthly periphyton development are defined primarily by the frequency of flood disturbances and the periphyton's interaction with the nutrients. it us of the streams as determined by catchment geology and land use. 2. Overall, mean monthly chl a concentration declined with increasing flood frequency (r= -0.711, P < 0.001), and seasonality in chl a was better defined at sites with a low frequency of floods. Chlorophyll a concentration was generally low throughout the year at sites with frequent floods (> 15 yr^?1). 3. No relationship existed between inorganic nutrient concentrations and catchment geology or land development. However, conductivity declined significantly as a function of the percentage of the catchment underlain by nutrient-poor, hard rocks (plutonic and fine-grained metamorphic rocks) (r= -0.515, P < 0.05), but increased significantly with the percentage of the catchment in intensive agricultural land use (r= 0.799, P < 0.001). 4. Cellular nutrient concentrations suggested that nitrogen was the nutrient most commonly limiting periphyton production. In turn, cellular N concentrations declined significantly with increasing percentage of the catchment in hard rock (r= -0.5M, P < 0.05) and increased with percentage of the catchments in intensive agricultlural land use (r= 0.948, P < 0.001). 5.The sites were classified into three enrichment groups (high, moderate and low) based on their land use and underlying geology. Cellular N concentrations varied significantly among these enrichment groups (ANOVA F= 14.661, P < 0.001). 6. Log chl a decreased significantly with increases in the annual 80th percentile velocity. However, the relationship was significantly different among the enrichment groups. 7. A stepwise multiple regression on the full dataset identified that the frequency of floods, proportion of the catchment in high-intensity agricultural land use and proportion in alkaline rocks were the most significant factors explaining variation in mean monthly chl a among the sites (r²= 89%). 8. Overall, the results showed that flood disturbance and catchment enrichment regimes are probably the principal axes of the habitat template of periphyton among the study streams, and could be used to explain and predict broad-scale differences in periphyton development among other temperate stream ecosystems.     

A Cenozoic time-scale — some implications for regional geology and paleobiogeography

Recent data generally substantiate the most recent incarnation of the Cenozoic time-scale (Berggren, 1969c). Newly obtained dates in the type section of the Chattian (Upper Oligocene) support a previous suggestion that a hiatus may separate the top of the stratotype Chattian from the base of the stratotype Aquitanian. The Orbulina Datum is placed at 16 my and the Globigerina nepenthes at 13.5 my. The junction of Eurasia and Africa in the early Miocene (ca. 18 my ago) and of Europe and Africa in the middle Miocene (ca. 15 my ago) markedly affected the Tethyan paleogeography and, concomitantly, the biogeographic dis tribution of larger and smaller Foraminifera, as well as various land mammal groups, including hominoids.     

Charles Lyell –"the father of geology"– as a forerunner of modern ecology

In 1830, Charles Lyell published the first volume of his influential book, "The principles of geology". Young Charles Darwin took the book on board the "Beagle" and, upon his return, acknowledged the contribution it made to his own research. Lyell did not believe in transmutation and evolution, and explained the differences in the fossil fauna between different geological formations by the accumulated environmental changes over a very long geological time. He describes ecological interactions of organisms with their biotic and abiotic environment in a language similar to current ecological concepts. Lyell may be seen as one of the forerunners of modern ecology.     

Distribution of benthic algae in the upper Illinois River basin in relation to geology and land use

• 1 Benthic‐algal distributions in the upper Illinois River basin, IL, U.S.A., were examined in relation to geology, land use, water chemistry and stream habitat using (detrended) (canonical) correspondence analysis, autecological metrics and indicator‐species analysis in order to identify the major environmental gradients influencing community variation.
• 2 Ionic composition and major nutrient [i.e. nitrogen (N) and phosphorus (P)] concentration of surface waters, salinity (Na‐Cl type), substratum type and physiognomic form of dominant species were primary factors contributing to variation in benthic‐algal assemblages of the basin. Basin geology was a significant contributing factor, but the explained variance associated with this factor was less than that related to land use.
• 3 Proportions of algal biomass consisting of cyanophytes, filamentous chlorophytes, halophilic diatoms and diatoms which utilize nitrogen heterotrophically were greater in eutrophic river segments than in less nutrient‐enriched segments. Composition of the benthic flora indicated meso‐eutrophic or eutrophic conditions throughout the basin; there were few diatoms indicative of hypertrophic waters. Shifts in diatom‐assemblage structure in response to nutrient loading provided an incomplete representation of the community‐response curve.
• 4 A weighted‐averages regression model based on total P and benthic‐algal abundances (all divisions included) yielded a highly significant correlation (r² = 0.83) between species‐inferred [WA_(tol)] and observed total P, with systematic bias (increased deviation of residuals) occurring only at concentrations greater than ～ 1.0 mg L^?1 total P. This result indicates that total P regression and calibration models can be predictable for a river basin receiving excessive loadings of phosphorus.

     

Observations of Lophelia pertusa and the surficial geology at a deep-water site in the northeastern Gulf of Mexico

Authigenic carbonate, precipitated in conjunction with biogeochemical activity associated with hydrocarbon and related fluid seepage, provides exposed and buried hard substrate on the crest and flanks of a low-relief mound located on the upper De Soto Slope in the northeastern Gulf of Mexico. Lophelia pertusa has successfully colonized some of this carbonate material. Individual colonies range in size from a few centimeters to over 1.5 m in diameter while aggregations of closely associated colonies with linear orientations were observed to attain 1.5–2 m in height and width and 3–4 m in length. Many of the aggregated colonies appear to be in the first phase of the `thicket' building stage described by Squires (1964). Colonies less than 50–75 cm in diameter were nearly always completely pure white. Larger colonies and the aggregated colonies are often light to dark brown in coloration at their base and center with many having only white terminal branches and some with no white corallum at all.