Detailed geologic mapping and subsurface study of late Pleistocene and Holocene sediments in northern Bear Lake Valley show at least four episodes of deposition of fluvial, marsh, bay, and lacustrine sediments. from oldest to youngest, these are the Ovid, Liberty, Wardboro, and Lifton episodes. These episodes are substantially different than those proposed by previous investigators. The informal term Bear Lake Formation is formally redefined here as the Bear Lake Group, and includes the newly defined Ovid Formation, Liberty Formation, lanark Formation, and Rainb= Gravel. The overlying Wardboro Loess, also defined here, provides a probably age of 11,000 to 8,000 years B. P. for widespread post-Wisconsinan deposition of loess in northern Utah and southern Idaho. The Ovid Episode began prior to 27,400 years B. P ., d=ing a warm, dry, climatic interval. Sediments deposited during the early part of the Ovid Episode include marsh and bay deposits of the l=er part of the Ovid Formation in northern Bear Lake Valley , probably similar deposits of the lCN~er part of the lanark Formation west of the Bloomington Scarp (on the west side of Bear Lake Valley), and marshy deposits beneath Bear Lake in southern Bear Lake Valley. West-sloping pediments at the north end of Bear Lake Valley, between Bennington and Georgetown, Idaho, and old alluvial fans, also may have formed at this time. The northern outlet of the valley was near 5990 feet at this time . Downfaulting along the Bear L3ke fault zone on the east side of Bear L3ke Valley, and prol:able eastward tilting affected the central valley during the Ovid Episode. At this time, deposition of deep-water carbonates, beneath Bear L3ke, prol:ably began in southern Bear L3ke Valley. Later, cooler- and Jl'Oister clirratic conditions of a Late Pleistocene glacial interval (Pinedale?) resulted in a shall& extension of this lake into northern Bear L3ke Valley during the Liberty Episode. Progradational, shallow-water sand deposits of the Liberty Formation show that Bear Lake attained its most recent maximum areal extent at this time. Simultaneous deposition of the Rainbow Gravel at the entrance of the Bear River into the valley, near Dingle, Idaho, and of the sandy, deltaic upper part of the Lanark Formation along the west side of the valley, reflected the increased addition of sediments, probably due to glaciation and higher stream discharges. The valley outlet was at an altitude near 5945 feet. Downcutting of the valley outlet and waning moist climatic conditions led to exposure of lake beds, increased effectiveness of the wind, and deposition of the Wardboro Loess during the Wardboro Episode. This loess prol:ably is correlative with the Niter Loess in Thatcher Basin (Gem and Gentile valleys, Idaho). It is slightly more than 8,000 C14 years old, and probably less than 11,000 year old. Recurrent faulting along the east margin (Bear Lake fault zone) and west margin (Bloomington Scarp) of the valley at the onset of the Lifton Episode led to a brief re- expansion of Bear Lake, and then a recession southward to its present position near 5923 feet. During this time, a series of beach ridges, successively younger southward, and undifferentiated sediments of marsh, bay, and stream origin, formed in northern Bear Lake Valley. The present valley outlet is near 5873 feet.

High altitude photography represents a new, potentially valuable, but largely untested information source for the interpretation of surficial deposits. It differs significantly in sensitivity and perspective from conventional aerial photography. It posesses different values and limitations which must be evaluated in their own right. The photography examined is shown to provide an excellent and reliable record of stream pattern geometry, and of stream flow regularity characteristics which are related to deposit slope form and material characteristics. The important image density component of the photographic record must be corrected for distortion but shows a consistent relationship with characteristics of near surface deposit hydrology. Photography and imagery from high or orbital altitudes will soon be a widely if not universally available information source. It is evident that such information can make a valid and useful contribution in geomorphic studies. This information is complimentary to existing techniques of data collection, and likely to realize substantial savings in time and efficiency while permitting wider application of findings. / Thesis / Master of Science (MSc)

The city of Wellington has a high population concentration and lies within a geologically active landscape at the southern end of the North Island, New Zealand. Wellington has a high seismic risk due to its close proximity to several major fault systems, with the active Wellington Fault located in the north-western central city. Varying soil depth and properties in combination with the close proximity of active faults mean that in a large earthquake rupture event, ground shaking amplification is expected to occur in Thorndon, Te Aro and around the waterfront. This thesis focuses on the area bounded by Thorndon Overbridge in the north, Wellington Hospital in the south, Kelburn in the west, and Oriental Bay in the east. It includes many of the major buildings and infrastructural elements located within the central Wellington commercial area. The main objectives were to create an electronic database which allows for convenient access to all available data within the study area, to create a 3D geological model based upon this data, and to define areas of different seismic subsoil class and depth to rock within the study area at a scale that is useful for preliminary geotechnical analysis (1:5,000. Borelogs from 1025 holes with accompanying geological and geotechnical data obtained from GNS Science and Tonkin & Taylor were compiled into a database, together with the results from SPAC microtremor testing at 12 sites undertaken specifically for this study. This thesis discusses relevant background work and defines the local Wellington geology. A 3D geological model of the central Wellington commercial area, along with ten ArcGIS maps including surficial, depth to bedrock, site period, Vs30, ground shaking amplification hazard and site class (NZS 1170.5:2004) maps were created. These outputs show that a significant ground shaking amplification risk is posed on the city, with the waterfront, Te Aro and Thorndon areas most at risk.