Abstract: An erodible marine or fluviatile sediment such as a sedimentary layer is stabilized by depositing on the sediment a non-setting paste-like slurry, for example, mud or clay containing a framework of gravel, using a laying head which is towed over the sea bed by a surface vessel. The slurry is mixed on the vessel and conveyed to the laying head through an underwater pipe. Distribution of the slurry from the laying head may be monitored by a television camera on the head.

Abstract: An open-ended seismic source for use in a liquid medium such as water is disclosed. The source includes a source of explosive gas, a firing chamber connected to the source, a capacitor discharge ignition system connected to the firing chamber for igniting the gas in the firing chamber, a barrel connected to the firing chamber, defining an explosion chamber and having an outlet at its lower end, a plurality of baffle plates fixed in the barrel near the outlet for permitting the exploded gas to enter the medium and for retarding the entry of the medium into the barrel, and a reaction plate attached to the barrel and disposed below the outlet so that the exploded gas entering the medium impinges on the plate and the recoil of the barrel is reduced.