Environmental Assessment
Volume B-3.1
Mine
Topography and Geomorphology
Ambatovy Project
15
January 2006
3.1
TOPOGRAPHY AND GEOMORPHOLOGY
3.1.1
Introduction
This section presents the Environmental Assessment for the effects of the mine
on topography and geomorphology, including unique topographic features, as per
the Ambatovy Project (the project) Terms of Reference.
3.1.2
Study Area
The mine Local Study Area (LSA) for topography and geomorphology is the
same as the terrestrial study area presented in Volume A, Figure 7.2-1. It
includes the mine and water intake pipeline disturbance areas, plus a 500 m
buffer around these areas in all directions. The LSA also includes the
Torotorofotsy Wetlands and the basin within 500 m of these wetlands.
3.1.3
Baseline Summary
The mine area includes the eroded remnants of a plateau located at an elevation
of about 1,100 metres above sea level (masl). The plateau is flanked to the west
by the broad alluvial plain of the Mangoro River and to the east by the
Torotorofotsy Wetlands and forested hills.
A ridgeline plateau flanked by hills and valleys characterizes the geomorphology
of the Ambatovy ore body. The plateau covers the northeastern portion of the
Ambatovy ore body due to the presence of an erosion-resistant ferricrete crust.
The plateau surface is fairly uneven with numerous depressions that form
ephemeral pools. The ferricrete layer thins on the flanks of the plateau and hills,
thus becoming more susceptible to erosion. Zones of weakness associated with
faults, fractures and dikes are present at the site.
The geomorphology of the western part of the mine area is characterized by
rolling hills and alluvium-filled valleys. The eastern part of the mine area
includes a portion of the Torotorofotsy Wetlands. The geomorphology of this
wetlands system is characterized by rolling hills and alluvium-filled valleys. The
valleys have been partially closed off, resulting in thick depositional sequences of
alluvial material.
