Abstract The central High Atlas Mountains of Morocco occupy the site of an Early (Lias) and Middle (Dogger) Jurassic seaway, which was oriented east-west across southern Morocco and filled by carbonate sediments. The axial part of this seaway was the site of deep-water deposition during the Lias. Because the rocks are neither severely deformed nor significantly dolomitized, the facies relations between the axial part of the basin, the slopes and the shelves are easily observed in the excellent outcrop exposures provided by the present-day desert climate. The Liassic deepwater carbonates were deposited in two major settings, basin and slope. (1) Basin: With the exception of the lowermost 10-20 metres, the deposits of the trough axis can be considered to be deep-water in origin. The oldest Liassic rocks within the trough axis are laminated micrites that record an early supratidal to subtidal environment of deposition prior to the onset of deeper-water conditions. Upward in the section, this sequence passes fairly abruptly into deeper-water lithoherms, massive micritic buildups that lack the coral and skeletal framework common in shoal-water reefs marginal to the trough. The lithoherms are overlain by an Upper Liassic sequence of rhythmic alternations of bedded marls and micrites that contain coccoliths and ammonites but lack the skeletal remains of benthonic organisms. The micrites contain a monotonous and low-diversity suite of trace fossils that indicate the presence of oxygenated bottom waters at the time of deposition. The rhythms represent the interlayering of pelagic deposits (micrites) and the distal, suspension loads of turbidity currents (marls). These Liassic deep-water deposits are overlain by a progressively upward-shoaling sequence of micrites and marls that are capped by coral reefs (Dogger age) representing the filling of the trough. (2) Slope: A sequence of Liassic turbidites that are essentially coeval with the basinal deposits represent deposition on the lower portion of the Jurassic slope of the High Atlas trough. Exposed on the southern slope is a sequence of turbidites that is almost one kilometre thick; the base of the sequence is not observed. The turbidite section is made up of materials apparently derived from numerous geographic locations. The oldest observed units are channeled, contain few Bouma cycles, and are interpreted to have been deposited in a mid-fan setting. The younger units contain many well-developed Bouma cycles that are interpreted to represent outer-fan deposition. These strata contain deep-water trace fossils.