GEOL
495 Death Valley Field Course 2000
Chapter 22. Hard rock pedology: silica cemented soils of arid regions
Introduction
Soils are overlooked
and undervalued as intrinsic and essential components of terrestrial ecosystems.
They can be used as environmental indicators because they integrate the
lithosphere, the biosphere, the hydrosphere, and the atmosphere, through
the course of time. Roy Simonson, a famous soil scientist from North Dakota
said, "the profile carries within itself a record of its history
for those who learn to read it" (Simonson, 1957). The "book
of soils" should be on the required reading list for all earth scientists!
The GEOL 495 Death Valley Field Course will acquaint all participants
with a fascinating set of landscapes. Soils, representing a staggering
range in age, blanket those landscapes, and regardless of ones "disciplinary
specialty" in geosciences, an investment in soils will provide many
dividends in terms of mineralogy, weathering, and geomorphology. There
are two major cemented horizons in arid region soils. Soils cemented by
calcite (CaCO3) are nearly ubiquitous and have been extensively studied
(calcic and petrocalcic horizons). Soils cemented by silica are not as
common, yet have intriguing genesis, and a few recent studies suggest
there is more to be learned. This paper describes the genesis, properties
and implications of soil horizons cemented by silica produced from surficial
weathering processes.
