The figure on the left is an amplitude-speed diagram of the generalised elevation solitary waves with |$E_b=1.5$|⁠, |$\tau=0.4$|⁠, |$\mathcal{R}=2$|⁠, |$\Lambda=3$| and |$\lambda=69.83$|⁠. The phase speed predicted by the dispersion relation is marked a circle on the axis. The long wave speed is marked as a diamond. The corresponding profiles for the waves which are marked by a cross in the left graph are shown in the right three figures.