I recently bought a property that has an embankment bordering one side of the property. At the top of the embankment, there is my neighbor's driveway, which appears to have been put in using a form of cut and fill. The embankment has started to cave in onto my property. We get along ok but there seems to be a disagreement developing between who's responsible for building a retaining wall. This cut and fill driveway was done before either one of us bought the homes. My stance is that I will accept responsibility up the the "root flares" of the trees that were buried when filling the embankment for their driveway. That is approximately the first 4' of height. I'm ascertaining that they are responsible from that point on, which is another 3' in height. They say I should pay for half the wall. I'm saying I will pay for what it would take to build the first 4', which, obviously would be much cheaper than going the full height of the wall. They did have the property line surveyed and most of the embankment is on their land. I think I'm being generous here and it is obviously not enough that I'm willing to contribute anything. My basic question here is how would anybody determine the original grade of the hill. I'm using the buried trees to determine the original grade. Also, I'm determining my responsibility, figuring that retaining walls rise in price exponentially not linearly. I am now semi retired but I am a third generation mason. Technically, I know what needs to be done but my concerns are legal concerns. They, obviously, have more resources than me and I don't want this to spin out of control and end up in court. Am I right or wrong with my position?