  Low temperature ultrasound velocity measurements are presented on the
frustrated spin system SrDy2O4 that allow us to define high resolution phase
diagrams with the magnetic field applied along all three principal axes. For
H||b, a region of field-induced long range order is delimited by a dome of
first-order phase transitions. An unusual magnetization process is observed
with significant irreversibility at very low temperatures when passing between
the low-field spin liquid phase and the long range ordered phase which we
attribute to large energy barriers. For H||c, the system appears to remain
effectively one-dimensional, exhibiting two transitions as a function of
magnetic field, but no finite-temperature long range order.
