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as Schweinfurth (1961) has demonstrated very well in this journal. Perhaps the geographical facet of the natural history of these birds which has most signi ficance is that of their migrations (fig. 1). This is best documented in the case of the Bass Strait muttonbird or Short-tailed Shearwater, Puffinus tenuirostris (Ser venty, 1953 & 1956; Marshall & Serventy, 1956). Preceded by their parents, the fledglings in their hunger leave their rookeries in late April and early May. Shortly afterwards casualties are picked up along New Zealand beaches. By May the birds are found in numbers in Japanese seas; in July-Septem ber, they are over Bering Straits, Alaskan coastal waters and even reach into the Arctic Ocean. The

(1966). Solution doline and subjacent karst doline. Australian Geographer: Vol. 10, No. 2, pp. 132-133.

(1970). Ingrown meander and Meander Cave. Australian Geographer: Vol. 11, No. 4, pp. 401-402.

Following earlier studies of snowpatch ac- tions, the lateral forces required to bend and tion in the northeastern cirque of Mt. Twynam break the steel rods ranged from the equivalent in the Snowy Mountains, Australia (Costin et of 1.6 to between 15.9 and 37.9 bars. These al., 1964), the magnitude of the snow forces forces are ample to account for the observed acting downslope beneath the snowpatch from snowpatch erosion at Mt. Twynam and exceed 1963 to 1971 was determined by studying the values reported for a snowpatch in British mode of failure of steel rods embedded in the Columbia and for some alpine glaciers. bedrock. Depending on site and snow condi

IN an R.G.S. Research Memoir just published,1 a theory attributing the origi of most of the Norfolk Broads to certain natural ph siographical processes was advanced. Briefly, it postulated that the formation of the broads could be explained in terms of a geologically very recent marine transgression of the Norfolk river valleys, during which a thick wedge of estuarine clay was laid down over the earlier valley peats; the broads themselves were thought to have been initiated as discontinuous lakes, lying in natural hollows in the peat filled with water ponded back between the flanges of the clay and the upland valley margin (by-passed broads), or in tributary valleys whose mouths were blocked by the clay (side-valley broads). This theory was based mainly on stratigraphical data obtained by boring through the alluvial deposits of the Ant and Bure valleys, and, although certain difficulties of detail were admitted, the conclusions reached seemed to be in very general accordance with the evidence at the time of submission of the manuscript in December 1950. In conjunction with the physiographical work in the Bure valley, a vegetational survey was also made, in which the present pattern of the plant communities was related directly to the gross and detailed stratigraphy of the underlying deposits.3 Between 1950 and 1952, this combined vegetational and stratigraphical work was extended by one of us (J. M. L.) to the Yare valley. Here, the increasing emphasis on the detailed interpretation of the vegetation in terms of the stratigraphy has required progressively much more closely set lateral bores than were employed to give the general physiographical outline in the Bure and Ant valleys, and, arising from this, important new data have come to light calling for a major reconsideration of the earlier hypothesis of the origin of the broads. Convincing stratigraphical evidence has now been obtained to suggest that all the Yare valley broads are artificial. Their basins are formed by undoubted excavations, usually reaching down to 3 metres or more below the present surface level, and presumably representing hollows left by deep extraction of peat in historical times. This view is further supported by cartographical and other data. A reconsideration of the evidence previously available from the Ant and Bure valleys, supplemented by additional observations since made in certain critical areas, now suggests that this explanation is of general application for the origin of the typical by-passed broads as a whole, though reservations, through insufficient data, must still be made in respect of the less numerous side-valley broads. A full presentation of the new evidence, and an assessment of the relationship of the artificial basins of the broads to the natural stratigraphy of the valleys, will be made as soon as possible. In the interim, it should be emphasized that the greater part of the story of the natural evolution of the river valleys, as distinct from the origin of the broads themselves, remains substantially unchanged from that presented in the Memoir.

IT is useful to define types of land forms and to classify them genetically, for we thus provide ourselves with a convenient f amework f concepts against which the geomorphological details of particular regions can be matched and which brings out the relationship and comparative importance of the various operative factors. Never? theless it is true that simple types which fall unequivocally into the single categories of the textbooks are rarities in the field; our classificatory systems often conceal, or at least scarcely hint at, the variety of character and complexity of origin of the entities with which we grapple in nature. During a recent study of the coastal geo? morphology of King Island, Tasmania, this observation was emphatically brought home to the writer by the heterogeneity of the numerous coastal dune lakes of the island. Since the enquiry was mainly directed at questions of changes in the relative level of land and sea, no detailed investigations of these lakes were made and the lack of soundings is particularly felt; however, the examples discussed here may serve to illustrate the general point with which this brief account begins. King Island (Fig. i) consists essentially of a faulted and tilted peneplain developed on Precambrian metamorphics, Cambrian volcanics and tillites, and Palaeozoic granites (Debenham, 1910; Waterhouse, 1915; Carey, 1946). The old erosion surface stands highest in the south-east at altitudes of 300 to 550 feet but declines westwards and northwards so that along a good deal of the coast the foundation of country rock lies not much above, and in parts below, sea level. Extensive development of coastal dunes has occurred and around much of the periphery of the island the dunes form a rim rising higher than the country immediately inland. In this context it is not sur? prising to find innumerable swamps, lakes and lagoons * scattered through the island. The dunes fall into different systems of varying age and composition, but for our present purposes it will be sufficient to distinguish two main groups?the New and the Old Dunes.