SECTIONAL TRANSACTIONS.— E. 569 



■which the population and industries may be induced to redistribute themselves about 

 a circumference rather than overcrowding along a few radii. It is often forgotten 

 that of the nine million people in the district, nearly U milhon are employed in 

 manufacturing. And the factories have gro-mi to a large extent on land that would 

 be better used for other purposes. New land can easily be made for such a purpose 

 by dredging for new harbour accommodation and filling up the marshes west of the 

 palisades and in southern Long Island. There is a project to make such a harbour 

 an industrial area in the future in the marshes of Jamaica Bay, a harbour big enough 

 to include the ports of Liverpool, Hamburg and Rotterdam. In the matter of cora- 

 mimications the engineers are equal to the problem. They are already building the 

 first bridge over the Hudson, the greatest suspension bridge in the world, as they 

 have recently built the Holland vehicular tunnels under the river. A great system 

 of belt lines around the city and of radial rail and motor highways will eventually, 

 it is to be hoped, lead to "the healthier spread of population over the area, giving 

 ample space in which the city may perform its economic functions more economically 

 and efficiently, and in which the people may lead a life healthier both physically and 

 socially. 



Presidential Address by Prof. J. L. Mybes on Ancient Geography in 



Modern Education. (See p. 99.) 



Afternoon. 

 Prof. Douglas Johnson. — Physiography of the Atlantic Coast of North 

 America. 



In eastern North America the old pre-Cambrian and Paleozoic rocks of the 

 Appalachian Mountains and Canadian Shield, lifted well above sea-level and deeply 

 dissected by stream erosion, are bordered on the east by a broad band of low-lying 

 sandy coastal plain deposits of much more recent age. In late Tertiary or Pleistocene 

 time a differential warping of the continent carried the northward part downward 

 at least 1,200 feet below its former level, thus permitting the sea to flow clear across 

 the sandy coastal plain belt and come to rest against the older and more deeply 

 dissected rocks to the west. Such is the origin of the two strongly contrasted types 

 of shore-Une scenery described in this paper. South of New York the sea still rests 

 against the low coastal plain, giving a simple shore-line characterised by sandy bars, 

 shallow lagoons and broad coastal marshes. North of New York the sea has reached 

 the older rocks, and there is a sudden change to the rocky, irregular coast where bold 

 peninsulas and countless islands alternate with deeply indented branchmg bays. Here 

 the low coastal plain is found under the sea, forming the famous fishmg banks of the 

 continental shelf. . 



Apparently this major differential submergence towards the north-east is only one 

 of several, perhaps many, oscillations of level which affected this coast m recent 

 geological times. Elevated terraces, bars and beaches are found at various levels 

 up to 400 or 500 feet, occasionally to 800 feet and more according to some observers. 

 These ancient strands are usually inclined, and some of them have been traced as 

 they descend below sea-level. The tilting, however, is not always in harmony with 

 that which carried the coastal plain below sea-level north of New York. Lvidently 

 differential movements of the land rather than eustatic shifts of sea-level are 

 responsible for the major features of this coast. 



Much interest attaches to the question as to whether the most recent movement 

 was one of emergence or submergence. Daly has inferred a recent eustatic shift of 

 sea-level permitting a land emergence of approximately 20 feet. The physiography 

 of the North Atlantic coast does not support this theory. Evidence is presented to 

 show that the last movement was one of submergence. 



The widely held theory that this submergence is still in progress is discussed. 

 Evidence for and against the theory is analysed, and it is concluded that the 

 submergence, which may have been due to an eustatic rise of sea-level consequent 

 on deglaciation, ceased several thousand years ago. , , • 



Attention is directed to the r61e of a fluctuating ' high tide surface in causing 

 fictitious indications of emergence and submergence, and it is argued that mean sea- 

 level likewise is not only an irregular surface but one sensitive to changes in the form 



