1 EARS5011 Engineering Geology and Site Investigation EARS5191 Ground Investigation Methods Broadway Area Site Investigation This report outlines the geology, geomorphology and the active processes that take place in a study area that is located nearby the village Broadway. Abstracts of the existing literature, aerial photography, and field mapping have been used in order to plot morphological maps and to identify any potential geotechnical problems. This study highlights the significant role that the stratigraphic succession plays in the creation of a variety of landslide types that affect the slopes, above the village Broadway. Broadway study area The study area is located on the escarpment slopes to the east of the village of Broadway (80 m-100 asl), in the vale of Evesham. It extends from the edge of the village to the top of the escarpment (~260 m asl), encompassing the A44 Broadway road in the south and Colliers Knapp (~180 m asl), to the north, (Fig. 1). Fig. 1 Satellite image of the study area. Topography of the study area The nature of the underlying geology is reflected in the topography of the site, (Fig. 2). The soft clays of the Lower Lias form an area of low ground within the base of the valley, while the more resistant bands of the Middle Lias silts, form the slopes of the escarpment above this Lower Lias valley. The change from Lower Lias clays to Middle Lias silts and sands gives rise to a change in slope which is often associated with the emergence of springs. Towards the top of the Middle Lias the presence of the Marlstone Rock Formation produces a prominent escarpment. This is evident at Colliers Knapp where topography changes, forming a distinct flat lithological bench. Colliers Knapp A44 Broadway
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EARS5011 Engineering Geology and Site Investigation
EARS5191 Ground Investigation Methods
Broadway Area Site Investigation
This report outlines the geology, geomorphology and the active processes that
take place in a study area that is located nearby the village Broadway. Abstracts of the
existing literature, aerial photography, and field mapping have been used in order to plot
morphological maps and to identify any potential geotechnical problems. This study
highlights the significant role that the stratigraphic succession plays in the creation of
a variety of landslide types that affect the slopes, above the village Broadway.
Broadway study area
The study area is located on the escarpment slopes to the east of the village of
Broadway (80 m-100 asl), in the vale of Evesham. It extends from the edge of the
village to the top of the escarpment (~260 m asl), encompassing the A44 Broadway
road in the south and Colliers Knapp (~180 m asl), to the north, (Fig. 1).
Fig. 1 Satellite image of the study area.
Topography of the study area
The nature of the underlying geology is reflected in the topography of the site,
(Fig. 2). The soft clays of the Lower Lias form an area of low ground within the base
of the valley, while the more resistant bands of the Middle Lias silts, form the slopes
of the escarpment above this Lower Lias valley. The change from Lower Lias clays to
Middle Lias silts and sands gives rise to a change in slope which is often associated
with the emergence of springs. Towards the top of the Middle Lias the presence of the
Marlstone Rock Formation produces a prominent escarpment. This is evident at
Colliers Knapp where topography changes, forming a distinct flat lithological bench.
Colliers Knapp
A44
Broadway
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Middle Jurassic
Upper Lias
Middle Lias
Lower Lias
Fig. 2, (above) The nature
of the underlying geology is
reflected in the topography
of the site (Modified by
Malcolm Whitworth, 2006).
Fig. 3, (left)
A distinct lithological
bench.
Above this bench the clays of the Upper Lias occupy a narrow zone of ground
rising gradually, small benches are present, as the result of lithological variability
within the Upper Lias (Fig. 3). This formation is overlain by limestones of the Middle
Jurassic Inferior Oolite Group.
Geology – Geomorphology of the study area
The geology of the study area can’t be observed on the surface due to the
presence of Quaternary deposits and vegetation. Existing literature was used in order
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to interpret the underlying geology. During the field mapping artificial cross sections
were used in order to help with the confirmation of the geology.
The geology of the study area is consisting of Lower – Middle Jurassic strata
(Table 1). These strata have a gentle easterly dip, although cambering and faulting
have produced local variations (Fig 4).
Unit Age (Ma) Thickness Lithological description
Solifluction deposits 0.1 ~2 metres Limestone rock gravel/cobbles within a silty