We consider semilinear parabolic equations of the form
$$
u_t=u_{xx}+f(u),\quad x\in R,t>0,
$$
where $f$ is a $C^1$ function. Assuming that $0$ and
$\gamma>0$ are constant steady states, we investigate the
large-time behavior of the front-like solutions, that is, solutions
$u$ whose initial values $u(x,0)$ are near $\gamma$ for
$x\approx -\infty$ and near $0$ for $x\approx \infty$. If the steady
states $0$ and $\gamma$ are both stable, our main theorem shows that
at large times, the graph of $u(\cdot,t)$ is arbitrarily close
to a propagating terrace (a system of stacked traveling
fonts). We prove this result without requiring
monotonicity of $u(\cdot,0)$ or the nondegeneracy of zeros of
$f$. The case when one or both of the steady states $0$, $\gamma$ is
unstable is considered as well. As a corollary to our theorems, we
show that all front-like solutions are quasiconvergent: their
$\omega$-limit sets with respect to the locally uniform convergence
consist of steady states. In our proofs we employ phase plane
analysis, intersection comparison (or, zero number) arguments,
and a geometric method involving the spatial trajectories
$\{(u(x,t),u_x(x,t)):x\in R\}$, $t>0$, of the solutions in
question.