and rear 3 panels this forms a shallow rectangular channel 7 at the lower extremity of the block flanked by feet 71 see fig2 moreover the inner edge 8 of the front 2 and rear 3 panels also extends upwardly to the same vertical level as the webs this feature permits the blocks to interlock vertically when stacked in courses and the upwardly extending edge 8 of the front and rear panels prevents concrete from oozing out from between courses of blocks when the finished wall structure is filled generally semi circular cut outs 9 are formed in the top edges of each of the webs 4 5 6 the purpose of the cut outs is three fold they provide a horizontal channel in which re bar may be laid before concrete is poured they provide channels that concrete may flow through when poured to ensure that the entire wall structure is filled and lastly they provide channels the concrete can harden in so that adjacent blocks in a course are rigidly locked together as can been seen most clearly in fig1 6 and 7 the ends 4 5 of the blocks 1 are profiled to interfit with one another at each end the web 4 5 is inclined slightly by 5 u00b0 10 u00b0 from perpendicular to the front and rear walls moreover where the end webs 4 5 meet the front and rear walls they curve with either a convex 10 or concave 12 portion such that when the blocks are laid end to end the flange 12 created adjacent the concave curve 11 will rest into the groove 13 created adjacent the convex curve 10 a bead of caulking or construction adhesive may be applied to the.