  We have obtained high resolution (FWHM = 4.4 km/s) Keck spectra of images A
and C of the gravitationally lensed QSO Q1422+231. The images are separated by
1.3" on the sky. In an absorption system at z = 3.538 gas column density
variations by an order of magnitude and velocity shear on the order of 10 km/s
are observed in the low ionization (SiII, CII) lines. The transverse separation
between the lines of sight in the absorbing cloud is estimated to be as small
as 26 parsec, corresponding to an effective angular resolution of 4
milliarcseconds as seen from the Earth. In contrast, the high ionization (CIV)
gas appears mostly featureless and thus must be considerably more extended. The
abundances of the elements carbon, silicon and oxygen appear to be close to the
solar values. The observation provides the first spatially and kinematically
resolved probe of the interstellar medium at high redshift on scales small
enough to be influenced by individual stars or star clusters. The mass
associated with the low ionization "cloudlets" is likely to be less than about
3000 M_solar and possibly less than 1 M_solar. The velocity shear seen across
the lines of sight is too large to be caused by galactic bulk motion, so the
velocity field of the low ionization gas must be strongly influenced by small
scale local gasdynamics. While it cannot presently be excluded that the
disturbances of the gas are due to high velocity outflows from the background
QSO, the observed velocity and density structure of the z=3.538 system is
consistent with our line of sight running through an expanding shell of gas,
possibly a supernova bubble or a stellar wind.
