If an aircraft hits a hard surface at high velocity this is exactly what to expect. If it hits a soft surface there may be no trace of the aircraft. That is certainly the case for a fighter jet which "tent-pegs" at transonic speed.
UAL 93 is another example of an accident with little to no identifiable pieces of wreckage. Frankly - even ValuJet 592 exhibited a similar level of debris even though it occurred in the everglades (swampy area).