Observations of the flow of dense fluid into uniformly density-stratified e
nvironments down plane slopes with small inclination to the horizontal (les
s than or equal to 20 degrees) are described, and a quantitative model for
such flows is presented. In these experiments the dense fluid is released a
t the top of the slope for a finite period of time. The resulting downslope
gravity current, or downflow, has uniform thickness with a distinct upper
boundary, until it approaches its level of neutral density where the fluid
leaves the proximity of the slope. Turbulent transfers of mass and momentum
occur across the upper boundary, causing a continuous loss of fluid from t
he downflow in most cases, and associated loss of momentum. The flow may be
characterized by the local values of the Richardson number Ri, the Reynold
s number Re (generally large), and of M = QN(3)/g('2), where Q is the (two-
dimensional) volume flux, N the buoyancy frequency and g' the (negative) bu
oyancy of the dense fluid. The model for the downflow describes the turbule
nt transfers in terms of entrainment, detrainment and drag coefficients, E-
e, E-d and k respectively, and the observations enable the determination of
these coefficients in terms of the local values of M and Ri. The model may
be regarded as an extension of that Ellison & Turner (1959) to stratified
environments, describing the consequent substantial changes in mixing and d
istribution of the inflow. It permits the modelling of the bulk properties
of these flows in geophysical situations, including shallow and deep flows
in the ocean.