Sedimentary rocks are a type of secondary rock because they are made of materials that have already been used as a part of rocks, plants, or animals. These usually accumulate as they are washed together by flowing water and deposited in layers. Compaction refers to the process by which the layers are pushed together by the weight of other layers deposited on top of them. Cementation refers to the process of the binding of the particles together by natural cements to form sandstone. Evaporation refers to water within the forming rocks that evaporated into the atmosphere causing minerals to crystallize forming rocks. For more information check the link below or the article on Rocks in World Book Encyclopedia.
in a limestone cave with stalactites, etc. aren't they formed by evaporation? the water dissolves the mineral and leaves them behind via evaporation from what i know. cave of the winds is a perfect example.