  Aims: We present observations from the Interface Region Imaging Spectrograph
(IRIS) of absorption features from a multitude of cool atomic and molecular
lines within the profiles of Si IV transition region lines. Many of these
spectral lines have not previously been detected in solar spectra. Methods: We
examined spectra taken from deep exposures of plage on 12 October 2013. We
observed unique absorption spectra over a magnetic element which is bright in
transition region line emission and the ultraviolet continuum. We compared the
absorption spectra with emission spectra that is likely related to
fluorescence. Results: The absorption features require a population of sub-5000
K plasma to exist above the transition region. This peculiar stratification is
an extreme deviation from the canonical structure of the chromosphere-corona
boundary . The cool material is not associated with a filament or discernible
coronal rain. This suggests that molecules may form in the upper solar
atmosphere on small spatial scales and introduces a new complexity into our
understanding of solar thermal structure. It lends credence to previous
numerical studies that found evidence for elevated pockets of cool gas in the
chromosphere.
