help!

I hava solve the problem I encountered last time.But now I encounter a new problem.For example, I have
two layers in my scene,one is stratum and the other is faultage.They are generated dynamically from true
data.I dont konw whether they are intersected or not and when they are intersected because they are generated dynamicly.We all know two layer’s intersection is a line.My question is how to seperate one layer into two layers(seperating from the line) dynamicly.How to seperate stratum into two layers from the faultage.