Complex sentence: Pyroclastic fall and surge are the two volcanic mechanisms of deposition, with hydraulic reworking of kimberlite from tephra cones and/or extra-crater fall and surge deposits.
Split into simpler sentences: Pyroclastic fall and surge are the two volcanic mechanisms of deposition. There are also deposits formed by hydraulic reworking of kimberlite from tephra cones and/or extra-crater fall and surge deposits.