Assignment on Bedrock
Bedrock depth is one of the critical site investigation procedures for seismic hazard analysis and
underground developments that may encounter varying rock formations. The rock that underlies looser
surface material. Bedrock is the solid, intact part of the earth’s crust, the outer layer 20-25 miles
thick that rests on the earth’s mantle.
In most places in Maine, the bedrock is concealed by a thin layer of unconsolidated sediment, soil, and vegetation.
An exposed portion of bedrock is often
called an outcrop.
The various kinds of broken and weathered rock material, such
as soil and subsoil that may overlie the bedrock are known as the bedrock beneath the soil cover
regolith is also known as engineering geology and its identification by digging.
Weathering may be physical or chemical and alters the structure of the rock and may cause it to erode and or alter over
time-based on the interactions between the mineralogy and its interactions.
Noise seismic data from Cape Cod produced clear, easily identified resonance frequency peaks. The interpreted depth and geometry of the bedrock surface correlate well with boring data and previously published seismic refraction surveys.
Conversely, the ambient noise seismic data from eastern Nebraska produced
subtle resonance frequency peaks, and correlation of the interpreted bedrock surface with
depths from borings is poor, which may indicate a low acoustic impedance contrast between the
weathered sedimentary rock and overlying sediments and the effect of wind noise on the seismic
Local estimates of bedrock depth likely could be improved through the development of
regional or study‐area‐specific regression equations relating resonance frequency to
To assess the subsurface strata and to locate the particular depth of rock, most of the site
investigation practices typically follow conventional programs which involve traditional drilling,
sampling, and laboratory testing as well as specific in-situ test.
The new empirical correlation is
established between the natural frequency of the ground calculated from the MM and the bedrock
depth from conventional borehole drilling. Understanding the global pattern of
underground boundaries such as groundwater and bedrock occurrence are of continuous interest to
Earth and Geosciences.