150 HOLDAHL, S. R. and MORRISON, N. L. , 1974. "Regional Investigations of 

 Vertical Crustal Movements in the U.S., Using Precise Relevelings and 

 Mareograph Data," In: R. Green (Editor), Recent Crustal Movements and 

 Associated Seismic and Volcanic Activity, Tectonophysics . Vol 23, No. 4, 

 pp 373-390. 



In the past two years, the National Geodetic Survey has been creating a 

 data base of vertical crustal movement information. The data elements are 

 relative elevation changes along lines of releveling which are used to produce 

 graphic displays on microfilm. In separate studies, the releveling data, 

 together with information extracted from mareograph records, have been used to 

 create two networks of velocity differences. The two networks one in the 

 vicinity of Chesapeake Bay and the other covering the Gulf Coast states, have 

 been adjusted in order to prepare maps showing the velocities of elevation 

 change. In the adjustments, the velocities derived from mareograph records 

 were treated as observations. The results indicate annual subsidence ranging 

 between -1.2 mm and -4.0 mm in the Chesapeake Bay area, with significant local 

 variation. In the Gulf Coast region there is generally slight subsidence 

 along the coast, ranging between 0.0 and -1.5 mm/year. Stability and slight 

 uplift is indicated to the north where bedrock reaches the terrain surface. 

 Anomalous subsidence of -7.0 mm/year occurs at New Orleans, Louisiana, and at 

 Houston, Texas, there has been several decimeters change in the last ten 

 years. (Authors). 



151 HOPLEY, D. 1984. "The Holocene 'High Energy Window' on the Central 

 Great Barrier Reef," In: Coastal Geomorphology in Australia (edited by B. G. 

 Thom) , pp 135-150. 



The concept of a Holocene 'high energy window' was introduced by Neumann 

 (1972). He suggested that on tropical coasts during the mid-Holocene , a pe- 

 riod of higher wave energy may have existed during the period when the present 

 level of the sea was being first approached by the Holocene transgression and 

 prior to the protective development of hermatypic coral reefs. It has also 

 been postulated (Stoddart et al . , 1978; Hopley, 1982) that the 'window' may 

 have operated on a more local scale on individual reefs with waves breaking 

 not on margins of an extensive reef flat as at the present time, but more 

 extensively over a shallowly submerged reef top prior to the development of 

 the reef flat. This paper examines the concept of a period of a higher wave 

 energy on the central Great Barrier Reef in the mid-Holocene and considers 

 some of the implications for coastal geomorphology. (Author). 



152 HOUGHTON, R. A. and WOODWELL, G. M. 1989. "Global Climatic Change," 

 Scientific American . Vol 260, No. 4, pp 36-44. 



This article emphasizes the role of carbon dioxide and methane in global 

 warming. The authors suggest that production of carbon dioxide and methane 

 from human activities has already begun to change the climate and that radical 

 steps must be taken to halt any further change. A series of key graphs 



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