  The exploration of the end of the Dark Ages will be one of the most exciting
field of the next decade. While most of the proposed observations must await
the next-generation telescopes, the observational window of the redshifted 21cm
line offers the possibility to investigate the physics of reheating and
reionization on a short term. Here we describe several possible signatures
detectable in the wavelength range 100-200 MHz. Among the physics that can be
investigated: the epoch of reheating and reionization; topology and timescales
of reheating; the nature of the ionizing sources; the baryon distribution at
redshift z~10. Such a good deal of information is within reach of present-day,
or near-future radio facilities.
