Geology topics
Publications and source records attributed to T. C. Winter.
Research on the hydrology of Mirror Lake, (north-central) New Hampshire includes study of evaporation. Presented here are those climatic data needed for energy-budget and mass-transfer studies, including: temperature of lake water surface, dry-bulb and wet-bulb air temperatures, wind speed, precipitation and solar radiation. Data are collected at raft and land stations. (USGS)
The drainage basin of Mirror Lake, New Hampshire is characterized by high knobs and ridges and steep land slopes. The lake is situated in the lower part of the basin, largely within glacial drift. Drift in most of the Mirror Lake drainage basin is till, which is as much as 50 meters thick, Crystalline bedrock underlying the drift is composed of schist, slate, and quartz monzonite of earliest Devonian age. These rocks are intensely folded and contain numerous fractures. Three small streams flow into Mirror Lake. Streamflow discharge into Mirror Lake differs between the two largest subbasins. Basin NW, which has a more round shape and thicker glacial drift than basin W, has greater stream discharge as well as greater sustained base flow. Ground water moves into most parts of Mirror Lake, and losses to ground water occur principally on the southeast side. Water-level data from piezometers and bedrock wells indicate dynamic ground-water movement within the fractured bedrock underlying Mirror Lake. These data also indicate very active interchange of ground water between bedrock and the overlying glacial drift. There are particularly strong hydraulic head gradients from the bedrock into the drift in the area between Mirror Lake and Hubbard Brook. (USGS)
An adjusted water budget prepared for Pine Lake, a candidate for lake-quality restoration, indicates that of approximately 790 acre-feet of water that enters the lake in a typical year, 410 acre-feet is from precipitation, 350 acre-feet is from surface inflow, and 30 acre-feet is from ground-water seepage. A nearly equal amount of water leaves the lake and of this, 130 acre-feet is by evaporation, 659 acre-feet is by surface runoff, and less than one acre-foot is by ground-water seepage. Based on these amounts of inflow and outflow, the theoretical water-renewal time of the lake is calculated to be 2.2 years. The contributions of inorganic nitrogen and phosphorus to the lake in a typical year from precipitation, surface inflow, and ground-water inflow is about 2,500 pounds of nitrogen and 49 pounds of phosphorus. (USGS)
The bedrock surface of east-central Minnesota is dissected by an intricate network of valleys. Outside the bedrock valley at site B, 3 mi (4. 8 km) from site A, 100 ft (30 m) of drift overlies the bedrock surface. Observation wells were installed at the two sites to determine the vertical ground-water movement between the various aquifer units and the lateral movement between the two sites. An aquifer test of the lowest valley-fill aquifer at site A showed that the observation well completed in the same aquifer as the pumping well responded immediately; whereas a lag of about 100 min occurred between the lower valley fill and uppermost body of sand and gravel. This indicates that the hydraulic connection between these two layers is poor at the immediate site. Test results show that the lower sand-and-gravel aquifer has a transmissivity between 14,000 and 27,000 ft 2 /d (1,300 and 2,500 m 2 /d). Although the hydraulic gradient is vertically downward in the valley, much of the drift fill is poorly permeable. This suggests that the quantity of downward-percolating water reaching the lowest valley-fill aquifer is relatively small at the test site. Because valley cut through a number of bedrock aquifers in the region, they could potentially be an important avenue of contamination from land-surface waste. In addition, the vast network of bedrock valleys in the Twin Cities area might cause contaminants to disseminate rather rapidly throughout a large area.
No abstract available.
No abstract available.
No abstract available.
A pollen diagram from Kirchner Marsh, southeastern Minnesota, records a continuous vegetation sequence from the time of Late Wisconsin ice retreat from the region. The late-glacial and early postglacial portions of the diagram are correlated with a radiocarbon-dated diagram from Madelia, Minnesota. Both diagrams show a series of maxima of pollen types in the early postglacial that suggest a significant climatic change at that time. The Kirchner diagram, in addition, shows high percentages of nonarboreal pollen later in the postglacial that indicate an advance of prairie elements into the area between 7200 and 5000 years ago.