Leonard Berry

WEATHERING OF GRANITE AND ASSOCIATED EROSIONAL FEATURES IN HONG KONG

The granite in Hong Kong is frequently weathered to a depth of more than 60 m (200 feet). The soil (or A and B horizons of pedology) is only a few feet thick. The very thick C horizon is considered as the weathering profile and is divided into four zones roughly parallel to the surface. Division is based on the percentage of solid rock and the character of the residual debris. Local variations in the weathering profiles are due to conditions of slope, subsurface water, vegetation, structure, and type of granite. Widespread modifications are the result of a varied climatic and geomorphological history. At Lai Chi Kok a wave-cut platform truncates a complete weathering profile. A Han tomb, discovered in the terrace, provides evidence of considerable subsurface eluviation in the upper weathering zone. Eluviation is shown to be important in the differentiation of local weathering debris and may give rise to a well-sorted residue. Studies in three areas show that thick, complete profiles were formed on gently sloping surfaces and are now variably dissected. Adjustment to structure has taken place within the weathering profiles in a small vertical range of denudation. Large pockets of core stones in residual debris of the upper zones are explained as abandoned portions of the weathering profile. Most gullying in Hong Kong occurs on slopes from 10°–40° in the region of deep weathering. It is due to instabilities in the upper weathering zones after partial dissection and deforestation. Surface erosion bares the subsoil to drying winds, which with partial eluviation from available free faces causes a contraction of the debris. Deep cracks are formed, and accelerated eluviation aided by storm runoff develops these into gullies.

The basal rock surface on weathered granitic rocks

Abstract Near, or at, the base of the weathering profile on granitic rocks there isoften a very rapid, sometimes sudden, change to massive bedrock. The upper limit of the bedrock is designated the Basal Surface. The basal surface does not demarcate the limit of weathering. Above it more highly weathered material allows ready access to sub-surface water while below it the slightly weathered bedrock is much less permeable. When open structural surfaces are confined to near the surface, rapid or prolonged weathering may be expected to develop a well-defined basal surface, regular on sheeting structures and irregular on blocky jointing. Basal surfaces exhumed by erosion may bear evidence of their origin, e.g. thepresence of well-rounded corestones in situ on their surfaces. A careful distinction should be made between exhumed basal surfaces and similar surfaces cut by surface agents of erosion.

Geographically weighted modelling of surface salinity in Florida Bay using Landsat TM data

An effective remote-sensing approach is needed for surface salinity monitoring in Florida Bay, a typical estuarine and coastal ecosystem (ECE). Yet, the non-stationary nature of surface salinity makes it difficult to model with conventional regression methods. A geographically weighted regression (GWR) approach was proposed to model surface salinity from Landsat Thematic Mapper (TM) imagery in this study. The models were constructed and validated with spatiotemporally matched field-surveyed salinity and TM imagery collected in February 1999. The GWR models reported high coefficient of determination (R 2) values and low root mean square errors (RMSEs) in validation. A 1999 model was also used to hindcast the surface salinity with TM imagery collected in December 1998 and validated with surface salinity collected at that time. The validation reported a reasonably low RMSE. It suggests a GWR approach, with field survey and remotely sensed data, may be useful in modelling and predicting the spatial variation pattern of surface salinity in Florida Bay, and could potentially serve as a less costly alternative or a supplement to field survey currently undertaken for salinity monitoring in the coastal areas of the Greater Everglades.

Erosion Surfaces and Emerged Beaches in Hong Kong

In the Hong Kong area two high sea-level stages at 15 and 5–6 m P.D.[1][1] are clearly marked. These appear to be the result of eustatic movements. A similar well-marked bench at —11 m P.D. represents a Late Pleistocene low sea level. At least one other period of low sea level, in which base levels were more than 60 m below P.D., occurred. Benches at 22 m, 40 m, and 71 m are found as remnants around most of the coast and are probably marine. Summit leveling at 130 and 230 m is common and may be marine or subaerial. A valley basement now abandoned at 430 m represents an old drainage line lightly incised into a subaerial surface indicated by summit heights of about 460m. [1]: #fn-1

The Earth Restoration Project: An Overview

Emerging from policy discussions at the National Academy of Sciences and the International Union for the Conservation of Nature and Natural Resources (IUCN), the ultimate objective of the project is to restore the integrity of the Earth System through the large scale application of proven scientific and indigenous knowledge; to focus initially upon critically important areas that are marginal to existing efforts in restoration – chiefly drylands, mountains, and upper-basin watersheds; to reinforce the integrity of associated social systems; to maintain an active program of related research, education, and outreach; and to carefully monitor program performance. The Project recognizes the varied and important contributions to environmental rehabilitation made by local populations, non-governmental organizations, governmental agencies, bilateral agencies, supranational bodies, and international organizations, and would prescriptively complement those efforts. Among the anticipated benefits of this project are the mitigation of global climate change; enhanced biological diversity and productivity; better adapted and more resilient societies, enhanced environmental stewardship; more dependable systems of food production; and a broad range of ecosystem services.

Salinity Assessment in Northeast Florida Bay Using Landsat TM Data

Human activities in the past century have caused a variety of environmental problems in the Greater Everglades of South Florida. In 2000, Congress authorized the Comprehensive Everglades Restoration Plan (CERP), a

Capacity Building to Sustainably Use Biodiversity in Dryland Regions of Latin America and the Caribbean

10.5-billion mission to restore the South Florida ecosystem. Many environmental projects in CERP need effective salinity monitoring in Florida Bay to provide a measure of the progress and effects of restoration on the ecosystem of the Everglades. Salinity modeling is also important given contemporary impacts and future projections of sea level rise. This study examined the potential for the Landsat Thematic Mapper (TM) sensor to serve as a regular salinity monitoring tool for Florida Bay. Spatially and temporally matched field data and TM imagery collected during Water Years 2004–2006 were employed to establish algorithms that quantitatively and qualitatively assess salinity in the northeastern area of the bay. The U.S. Geological Survey (USGS) defines Water Year as the 12-month period from October 1 of one year to September 30 of the following year, and designates it by the calendar year in which it ends. The empirical algorithms for quantitative assessment of salinity generated a reasonable level of accuracy and a neural network based technique for qualitative assessment presented a promising result. We conclude that Landsat TM can be used as a monitoring tool to assess salinity with desirable spatial and temporal resolution and accuracy. Extendibility of algorithms for the entire Florida Bay will be tested in the future.

Structure and form of Cheung Chau island, Hong Kong

Latin America and the Caribbean are well known as the site of great biodiversity, but the focus of attention is most of ten on the admittedly important world heritage of the tropical and mountain rainforests and wetlands of the region. This paper directs attention to the globally significant biodiversity of the arid and semiarid parts of the region. The area includes some of the driest deserts in the world in Chile and large areas of semiarid subtropical conditions, some of which are influenced by the proximity to, and the influence of, the Andean mountain chain. The paper reviews the current funding priorities in the region, attempts in a general way to identify biodiversity conservation needs in terms of networks and institutions and addresses the most effective processes to build on and expand the already sound capacity in the region.

The Nile in the Sudan

A study of Cheung Chau Island has revealed a close adjustment between the form of the island and the geological structure. The island is made up of dominant granite cut by granite-porphyry and dolerite dykes, which are affected by later faulting. A theory of progressive emergence is put forward for the denudation chronology of the area and the various forms related to the former submergence have been mapped. The relation of coastal and inland forms to structure is considered, and the evolution of the coast is outlined.