yes your situation is a bit different but the method / concept of getting the value is the same. i.e. you're trying to find a value (the depth) that is associated with a maximum (the displacement).
for your report try this:
1) create a formula like this...
totext({your displacement field},2) + '|' + totext({your depth field},2)
2) in your cross-tab keep your Row as the datefield but add the new formula into the Summarized Fields dialogue twice but change the summary Types to Maximum
3) preview the report and right click on the first summary and choose Format Field > Common Tab > Display String and use something like the following to give you the maximum displacement associated with the date
split(curentfieldvalue,'|')[1]
4) now right click on the 2nd summary and go to the Display String to give you the Depth associated with the maximum displacement
split(curentfieldvalue,'|')[2]
-jamie