Diatoms can be difficult to identify accurately in optical
microscopes, but are easily viewed with SEM equipment. They are especially
sensitive ecological indicators and can be used to determine environmental
contrasts in modern and fossil hot springs. At Lake Bogoria in Kenya,
Anomoeoneis sphaerophora, for example, occurs in saline lake margins fed
by hot springs. Other species are directly associated with different parts
of the hot springs, such as Nitzschia latens and Navicula cuspidata. Studies
of these diatoms have shown that modern diatoms can be used to differentiate
subenvironments. These data can then be used to reconstruct fossil systems.
The Bogoria hot springs also contain fossil root systems
that are preserved by a variety of mineralogies, identified by SEM form
and EDX element composition. The silica microspheres are developed in cell
tissues through evaporative concentration of silica-rich fluids. A unique
aspect of the area is that well developed fluorite crystals are also associated
with root casts exposed to the fluoride-rich waters.
