A segmental earth retaining wall block having a front side, a top side with a transversal tongue of a given width projecting from it, the tongue extending at a first distance from the front side, and a bottom side with a transversal groove made in it, the groove being sized to receive the tongue of another similar block positioned below and thus to allow stacking of the blocks. The groove extends at a second distance from the front side that is smaller than the first distance, and the first and second distances are selected so that the tongue and the groove are offset with respect to each other over a distance that is smaller than the width of the tongue. The tongue is provided with a splitting groove sized and positioned to allow splitting of the tongue with a splitting tool along a transversal line that is positioned to permit the remaining portion of this tongue to fit into the groove of a further similar block stacked on top of the present block with the front side of this further similar block extending in a same vertical plane as the first side of the present block.