ing inside playa boundaries but common in uplands
greatly to the consistency and cost effectiveness of pla-
close to playas. For soils, playa soils from the Lassen
ya delineation do exist. Laboratory work on playa sedi-
County Soil Survey were described as "deep, somewhat
ments specifically investigating the relation between
poorly drained soils that form a hard, vesicular, crusted
hydrology and (1) surface crack formation, (2) crust
surface layer when dry." For hydrology, the most reli-
formation (both biotic and abiotic), and (3) possible lay-
able field indicators during dry times of the year were
ering phenomena, would produce readily usable infor-
the presence of deep soil cracks and a thin salt encrus-
mation for playa delineation in the field. Further
tation on the soil surface.
laboratory work on the chemical and microstructural
Using these criteria, five types of playas were delin-
responses of playa sediment to inundation and satura-
eated:
tion would yield tools for instances in which other
1) Playas: Isolated topographic depressions (0.30
indicators were unreliable. Studies on the effect on veg-
0.91 m [13 ft] lower than surrounding uplands) lacking
etation of the relationship between salt accumulation
vegetation and with salt-encrusted, cracked surfaces.
and hydrology would also produce useful indicators.
2) Riverine playas: Similar to playas, but single, nar-
row, linear, meandering depressions with a possible
LITERATURE CITED
directional water flow.
3) Playa complexes: Playa-like areas dotted with
Akili, W., and J.K. Torrance (1981) The development
numerous upland mounds supporting upland vegeta-
and geotechnical problems of sabkha, with preliminary
tion. To be included in this classification, the playa-like
experiments on the static penetration resistance of
cemented sands. Quarterly Journal of Engineering
surface represented 50% or more of the total area.
Geology London, 14: 5973.
4) Uplands containing playettes: These areas resem-
ble playa complexes, except that the playa-like surface
Bacon, D., T. Cahill, and T.A. Tombrello (1996) Sailing
stones on Racetrack Playa. Journal of Geology, 104:
represents less than 50% (and typically less than 20%)
of the area.
121125.
Barbour, M.G., and W.D. Billings (1988) North Ameri-
5) Playa-like uplands: These are nonvegetated areas,
can Terrestrial Vegetation. Cambridge: Cambridge Uni-
but without distinct playa soils. They are generally
sandier than playa soils, and the surface cracking and
versity Press.
salt encrustation are not as pronounced. A further dis-
Barbour, M.G., and J. Major (1990) Terrestrial vegeta-
tinguishing feature is that the upland mounds are not
tion of California. California Native Plant Society, Spe-
as distinctly steep as in the playa complexes. It is
cial Publication Number 9.
thought that these areas may pond briefly, but drain
Belk, D., and J. Brtek (1995) Checklist of the anostraca.
Hydrobiologia, 298: 315353.
quickly.
The Sacramento District of the Corps assumes juris-
Belk, D., and J. Brtek (1997) Supplement to "Checklist
of the anostraca." Hydrobiologia, 359: 243245.
diction over types 13.
Blank, R.R., D.E. Palmquist, and J.A. Young (1992)
Plantsoil relationships of greasewood, torrey saltbush,
CONCLUSION
and Allenrolfea that occur on coarse-textured mounds
on playas. In Proceedings of Symposium on Ecology
A review of the technical literature on playas has iden-
and Management of Riparian Shrub Communities, Sun
tified unambiguous morphological features associated
with inundation and/or shallow saturation. However, none
Valley, Idaho, p. 194197.
of this material addresses sequential episodes of inun-
Blodgett, J.C., and J.S. Williams (1990) Land subsid-
dation for use in establishing the duration or frequency
ence and problems affecting land use at Edwards Air
of flooding needed to establish OHW. Further, the lon-
Force Base and vicinity, California. U.S. Geological Sur-
gevity of these features is questionable; there are no
vey, Water-Resources Investigations Report 92-4035,
data to suggest that the absence of such features may
Sacramento, California.
be used as evidence for the absence of inundation or
Boettinger, J.L. (1997) Aquisalids (Salorthids) and other
saturation, and some features may be greatly con-
wet saline and alkaline soils: Problems identifying aquic
conditions and hydric soils. In Aquic Conditions and
founded by factors such as soil chemistry. Conse-
Hydric Soils: The Problem Soils (M.J. Vepraskas and S.W.
quently the delineation of playas is currently based on
a mixture of meager technical data, best professional
Sprecher, Ed.). Soil Science Society of America, Madison,
judgement, and site-specific inferential study.
Wisconsin, Special Publication No. 50, p. 7997.
While some site-specific work will probably always be
Briere, P.R. (2000) Playa, playa lake, sabkha: Proposed
definitions for old terms. Journal of Arid Environments,
required because of the inherent variability among pla-
yas, productive lines of research that would contribute
45: 17.
22
to contents
Previous Page
