Geology of Urban Watersheds - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 38

Topographic watershed divide

Sinkhole throat
Swallow hole
Bedrock
collapse
sinkhole

Dissolution sinkhole Sinking stream

Sinkhole pond

Blue hole
spring

Karst window

Cave
spring

Cave

FIGURE 2.17
Common features of karst topography. (From Kentucky Geological Survey, Karst land in Kentucky, http://
www.uky.edu/KGS/water/general/karst/index.htm, (accessed August 29, 2009), 2009.)

N

0 1000 km

FIGURE 2.18
Extent of karst in the continental United States. (Differences in shading represent different regions and forma-
tions) (From United States Geological Survey, Eolian history of the United States, http://esp.cr.usgs.gov/info/
eolian/task1.html (accessed February 26, 2010), 2009c.)

2.3.2 Non-Clastic Chemical Sedimentary Processes

Non-clastic sedimentary processes involve the precipitation of minerals from water by
inorganic or biological processes. Limestone, dolostone, chert, and evaporites are the most
common sedimentary rocks formed. Proper identification of sedimentary deposits from
chemical processes requires the identification of the primary mineral.
As noted by Deer et al. (1966), common minerals of chemical sedimentary rocks include

• Limestone—composed of calcium carbonate (CaCO 3 ) and predominantly forms in
a marine environment from the accumulation of shells, shell fragments, or from
the direct precipitation from water (usually seawater).
• Dolostone—composed of magnesium-calcium carbonate (CaMg[CO 3 ] 2 ) and asso-
ciated with a marine-type environment.