Dean A. McManus

The Two Paradigms of Education and the Peer Review of Teaching.

Before a faculty member undergoes a peer review of teaching, both the reviewers and the faculty member should understand the two paradigms of education–the Teaching-Centered Paradigm and the Learning-Centered Paradigm, because the paradigm chosen, even tacitly, by a faculty member determines how he or she educates students. Although the distinction between the paradigms has centered almost entirely on teaching methods and classroom environment, the differences between them are more fundamental. The paradigm determines the instructors educational assumptions, educational goals, and assessment of results. Further, it determines the instructors sense of educational responsibilities, the relationship with students, and motivational and mentoring responsibilities. Therefore, the peer review of an instructor teaching with one paradigm by reviewers who teach with the other risks being unfair and misleading. Complicating the issue are the .invisibility. of the Teaching-Centered Paradigm to most instructors who use it and the common use of Learning-Centered teaching methods or aims by instructors who still follow the Teaching-Centered Paradigm. Owing to the increase in numbers of Learning-Centered instructors, peer review now requires greater sensitivity by reviewers than before. Aligning the appropriate tools for peer review with the teaching implications of paradigm choice is the object of this paper.

Modern versus Relict Sediment on the Continental Shelf

Sediment (deposits of unconsolidated material) on the continental shelf is affected by two groups of sedimentary processes that differ in nature and disposition with time. One of these groups of processes supplies particles to the shelf, and if it does so at present, we may say that the particles are now being supplied; otherwise the particles were supplied in the past. The other group of processes distributes the particles on the shelf to form them into sedimentary deposits; if this group is operating at present, we may say that the resulting deposits are modern; otherwise they are relict. The interrelations of these two groups of processes are used to classify shelf sediment into five classes of sediment process-age: Neoteric sediment is a modern deposit that consists of particles now being supplied to the shelf. Proteric sediment is a modern deposit that consists of particles supplied to the shelf before the present. Amphoteric sediment is a modern deposit that consists not only of particles now being supplied to the shelf but also of particles that were supplied to the shelf before the present. Palimpsest sediment is a relict deposit that mainly contains particles supplied to the shelf before the present but also includes some particles now being supplied to the shelf. And relict sediment is a relict deposit that consists solely of particles supplied to the shelf before the present. At a given locality, the duration of present conditions varies with the intensity of the sedimentary processes; between localities, the duration varies inversely with the rate of sediment accumulation. This classification can be used in conjunction with measurements of sedimentary processes on the shelf. For example, measurements of processes that distribute sediment to form deposits may be of direct use in explaining neoteric, proteric, or amphoteric sediment but of no use in explaining palimpsest or relict sediment. And measurements of processes that supply particles to the shelf may be of direct use in explaining the presence of particles in neoteric sediment and of some but not all particles in amphoteric or palimpsest sediment but of no use in explaining particles in proteric or relict sediment. These expanded concepts that concern modern and relict sediments are aimed at assisting the extrapolation of measurements of sedimentary processes into unmonitored areas of the shelf.

Continental Shelf Sedimentation in an Arctic Environment

A factor analysis of 579 bottom sediment samples from the Continental Shelf in the Chukchi and northeastern Bering Seas identified three factors that “explain” 92 percent of the variation of ten granulometric variables. Factor I represents deposition of silts and clays by settling from the water column. Although Factor I is extensively distributed in the areas of quieter water, the extreme values occur where there is an abrupt reduction in transporting capacity. Factor II represents both the provenance of the sand and the deposition or modification of sands by nearshore processes. Factor III represents beach processes and also several processes producing a poorly sorted sediment. The silts and clays from the Yukon River cover the bottom of Norton Sound and are encroaching onto the relict sands of the Chirikov Basin. Together with the muds from other Alaskan rivers, the Yukon sediment is also transported into the Chukchi Sea, in both the coastal water and offshore water. The coastal flow leaves the coast at Point Hope, diverges, and enters the complex circulation in the Chukchi Basin that is controlled by regional winds. Depending upon the atmospheric pressure distribution, the currents may carry much of the sediment off the shelf down Herald Canyon or into the East Siberian Sea, or the bottom water and sediment may remain in residence on the shelf even to a point of minor stagnation of the circulation. Sufficient mud has been deposited to floor the basin. The compensation current from the East Siberian Sea may be a more significant sediment supplier than previously thought, and the northward flow of the Bering Strait current from Point Hope to Point Barrow may be sporadic. The nearshore sands of the southeastern Chukchi Sea are modern, wave sorted in places, and current deposited in other places. Along the Siberian coast and in the northeastern Chukchi Sea, the sands are relict and residual. Residual sediment also occurs on Herald Shoal. Although the seas are ice covered for 9 to 10 months annually, ice rafting is not a dominant sedimentary process. Deposition of fine sediment may occur during this time by settling from the homogeneous water.

Blanco fracture zone, northeast Pacific Ocean

Abstract Blanco fracture zone is shorter and narrower than other fracture zones in the eastern Pacific, and instead of paralleling the trend of the nearby Mendocino zone, it converges with the Mendocino at an angle of 30–50°. Study of the bottom topography of the Blanco zone suggests an amount and direction of offset along the purported transcurrent fault of the zone (275 km, left-lateral) different from that arrived at in previous works dealing with the magnetic anomalies in the area (110 km, right-lateral). The cause of this discrepancy is still unknown. The anomalous non-parallelism of the Blanco zone to the Mendocino zone may be explained by considering the Blanco zone to be one of several northwest-trending Miocene structures in this area, although it is possible that future studies may reveal the zone to be an en echelon arrangement of east-west faults. Diverse interpretations relating transcurrent movement along the Blanco zone to the regional tectonic pattern are possible because of a lack of definitive criteria.

Physiography of Cobb and Gorda Rises, Northeast Pacific Ocean

Two oceanic rises, present near the coast of the northwestern United States, are bordered on the east by the continental rise, on the west by abyssal hills and plains, and on the north and south by fracture zones. A third fracture zone separates and smaller zones transect the rises. Physiographic provinces on the rises include a crest province with a median valley, a flank province, and a transition province. The crest of Gorda Rise has greater relief and a better-developed median valley and associated positive magnetic anomaly than the Cobb Rise. Both may be Miocene or older. Their physiographic provinces, particularly those of Gorda Rise, are more similar to those of the Mid-Atlantic Ridge than to those of the East Pacific Rise. In previous studies, Cobb and Gorda rises have been interpreted as northern extensions of the East Pacific Rise in the southeast Pacific. Alternative interpretations are that the northern rises may be a rejuvenated segment of an older arcuate rise off the west coast of the United States, or that they may form an auxiliary ridge associated with the Mendocino Fracture Zone and are possibly unrelated to the East Pacific Rise.

A shallow seismic-profiling survey of the northern Bering Sea

Abstract During the summer of 1967 shallow continuous seismic-profiling records were obtained along 3,900 km of track in the northern Bering Sea. Reflections were recorded from five different horizons. The deepest reflector probably represents pre-Tertiary volcanic, sedimentary, and metamorphic rocks and some Tertiary volcanic rocks. It is overlain by a thick sequence of sediments represented by parallel reflectors. These deposits have undergone faulting and gentle folding. In the western half of the northern Bering Sea their upper surface has been subaerially eroded, whereas in the eastern half it has not. In the subaerially eroded region near the Siberian coast there are indications of buried glacial deposits. Overlying the parallel reflectors near the Yukon delta is an extensive Yukon River deposit of presumed Late Quaternary age. The present sea floor contains features suggesting both erosional and constructional remains of former sea level stillstands.

Sea-level data for parts of the Bering-Chukchi shelves of Beringia from 19,000 to 10,000 14C yr B.P.

Abstract Sea-level changes in Beringia are especially significant because they affect the migration of land plants and animals between Asia and North America, and marine plants and animals between the Pacific and Arctic oceans. Previous studies of cores from the Bering and Chukchi shelves produced sea-level curves. Evaluation of these data suggests that nine of the radiocarbon-dated estimates of sea-level position are most reliable for the time period 19,000 to 10,000 yr B.P. The trend of these nine points is proposed as the basis for a regional sea-level curve for central Beringia. Constraints on the data must be noted, however, by anyone using them.

Origin and Distribution of Sands and Gravels on the Northern Continental Shelf Off Washington

ABSTRACT Nearshore sands (<25-30 meters) on the northern Washington shelf (Grays Harbor-Cape Flattery) have high percentages of clinopyroxene, garnet, and amphibole that indicate local sediment supply along the coast. Orthopyroxene, which characterizes the Columbia River sediment, does not form a significant proportion of these sands, as it does in the nearshore sands to the south, between Grays Harbor and the Columbia River. In contrast to these differences, a heavy mineral-rich zone at 44 to 51 m has relatively abundant orthopyroxene all along the shelf, especially in the southern part. This feature indicates that orthopyroxene-rich sediments were more abundantly supplied to the southern part of the shelf in the past and/or the northward sediment drift was stronger than at present, possib y due to the lack of headlands. Although the Columbia River is the most obvious source for the sediment, the Chehalis River could have delivered considerable quantities of sediment during the Pleistocene. The mineral composition of the sediments from these two sources may have been somewhat different. Glacial outwash exiting through Grays Harbor during lowered sea level supplied the gravel found on the adjacent inner, middle and outer shelf. Except near the Columbia River where a blanket of modern silt covers the shelf, anomalously coarse deposits or zones rich in heavy minerals are found discontinuously at depths of 18 to 33 m, 44 to 51 m, 73 to 82m and 165 to 180 m. The latter deposit is at the shelf break but the other three depths may represent stillstands of lowered sea level. Corre ations of these depths with other shelves should not be attempted because of complex, local Quaternary tectonism.

Continental shelf sediment, northwestern United States

ABSTRACT The Columbia River is the dominant sediment source for the continental shelf near the northwestern United States. The Washington continental shelf is nearly covered by modern sediment derived from the Columbia River. This sediment moves generally northward away from the river mouth. Sand generally occurs at depths less than 90 m. Coarse silt occurs in deeper water. The modern sediments generally contain less than 1.5 percent CaCO3 and less than 1 percent organic carbon. Relict sediment covers the continental shelf off southern Vancouver Island and occurs along the seaward margin of the continental shelf off southern Washington and northern Oregon. These relict sediments exhibit complicated patterns of grain-size distributions and, in general, contain more organic carbon and calcium carbonate than the modern sediment.

Pleistocene drainage patterns on the floor of the Chukchi Sea

Abstract It is proposed that the lack of bathymetric continuity in a submarine valley crossing a continental shelf is the result of deltaic deposition and may therefore be used to recognize periods of a lesser rate of sea-level rise or a period of sea-level stillstand. Using this criterion three stillstands may be recognized in the bathymetry of the Chukchi Sea: ( 1 ) present sea level (past 3,000–6,000 years); ( 2 ) −18 to −24 fathoms (12,000 years B.P.) and ( 3 ) −29 fathoms (estimated between 13,000 and 17,000 years B.P.).