Example SLD classification
<?xml version="1.0" encoding="ISO-8859-1"?>
<StyledLayerDescriptor xmlns:xlink='http://www.w3.org/1999/xlink'
xmlns:gml='http://www.opengis.net/gml'
xmlns:ogc='http://www.opengis.net/ogc'
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
version='1.0.0'
xsi:schemaLocation='http://www.opengis.net/sld StyledLayerDescriptor.xsd'
xmlns='http://www.opengis.net/sld' >
<NamedLayer>
<Name><![CDATA[GeologicAge]]></Name>
<UserStyle>
<FeatureTypeStyle>
<!--Rules-->
<Rule>
<Title> > 159.1 AND <= 344189.1</Title>
<Filter xmlns="http://www.opengis.net/ogc">
<And>
<PropertyIsGreaterThanOrEqualTo>
<PropertyName>LAND_KM</PropertyName>
<Literal>159.1</Literal>
</PropertyIsGreaterThanOrEqualTo>
<PropertyIsLessThanOrEqualTo>
<PropertyName>LAND_KM</PropertyName>
<Literal>344189.1</Literal>
</PropertyIsLessThanOrEqualTo>
</And>
</Filter>
<PolygonSymbolizer>
<Fill>
<CssParameter name="fill">#680000</CssParameter>
</Fill>
<Stroke/>
</PolygonSymbolizer>
</Rule>
<Rule>
<Title> > 344189.1 AND <= 688219.2</Title>
<Filter xmlns="http://www.opengis.net/ogc">
<And>
<PropertyIsGreaterThan>
<PropertyName>LAND_KM</PropertyName>
<Literal>344189.1</Literal>
</PropertyIsGreaterThan>
<PropertyIsLessThanOrEqualTo>
<PropertyName>LAND_KM</PropertyName>
<Literal>688219.2</Literal>
</PropertyIsLessThanOrEqualTo>
</And>
</Filter>
<PolygonSymbolizer>
<Fill>
<CssParameter name="fill">#B20000</CssParameter>
</Fill>
<Stroke/>
</PolygonSymbolizer>
</Rule>
<!--/Rules-->
</FeatureTypeStyle>
</UserStyle>
</NamedLayer>
</StyledLayerDescriptor>