the regional lithodynamics of the ocean. Naturally, it is both difficult and unreasonable to draw a sharp distinction between these three methods of investigation.
Placing lithodynamics completely into the field of the physical geography, geology
or physics would also be unreasonable and not natural. Each of these branches of
science considers the same phenomena in the ocean from their viewpoints; they
have their own subjects and own tasks of research. Clastic material, undoubtedly,
should be studied by marine geology, while its transport is a subject of
lithodynamics. At the same time, regional lithodynamic systems are, undoubtedly,
the constituent parts of the complexes called ocean or ocean-floor landscapes, and
from this point of view these systems should be studied by the physical geography
of the ocean. Elucidation of the main regularities of origin, development and
movement of sediment transport in the lithodynamic systems is a task of the
ocean dynamics of the contact zone, which is a branch of marine physics or
geophysics in a broad sense.
Let us return to the description of the main tasks and concepts of the ocean
contact zone dynamics or lithodynamics of the local lithodynamic systems. The
construction of models of local systems should result in the expression of sediment
transport discharge. This expression should be given in a form, suitable for the
discharge under given conditions of the contact zone. These conditions include such
factors as the nature of the underlying surface, energy parameters and structure of
hydrodynamic field for hydrogenic processes, floor gradient and composition of the
bottom and moving sediment for suspension flows and gravitational displacements.
The next stage of the investigation of the contact zone lithodynamics is the
determination of the influence of unstable environment of the contact zone on
transport discharge. At this stage, the main concept of the lithodynamics of any
system arises, which is the discharge gradient. The value and sign of the gradient
determine the morphologic effect or system performance on the given area and
processes of sediment differentiation on the flow route according to the hydraulic
coarseness.
If a constant speed is maintained by exogenous forces in a flow, moving above
the washed-out floor, this flow becomes saturated with solid load over a part of its
route, and during subsequent motion, the interchange between the sediment and the
floor occurs, while the load, applied in the saturation area, remains constant.
However, even after the saturation the flow still consumes energy to overcome
resistance to its motion at a given speed to maintain the entire motion of the solid
load. When the energy supply to the flow decreases, the speed becomes slower,
negative discharge gradient develops, and a part of sediment is deposited simultaneously with its differentiation in accordance with the hydraulic coarseness. If the
energy decrease is smooth, deposition will proceed over some portion of the route
until the balance is gained between the consumed and received energies. If the
energy supply stops completely or decreases sharply, a local accumulation form
will result.
It should be noted that a quantitative solution, which requires the knowledge of
the flow discharge parameters, is possible only in rare cases, related to the dynamics
of the local systems. In the lithodynamics of the regional systems, it is possible to
122
R.D. Kosyan and B.V. Divinskiy
Placing lithodynamics completely into the field of the physical geography, geology
or physics would also be unreasonable and not natural. Each of these branches of
science considers the same phenomena in the ocean from their viewpoints; they
have their own subjects and own tasks of research. Clastic material, undoubtedly,
should be studied by marine geology, while its transport is a subject of
lithodynamics. At the same time, regional lithodynamic systems are, undoubtedly,
the constituent parts of the complexes called ocean or ocean-floor landscapes, and
from this point of view these systems should be studied by the physical geography
of the ocean. Elucidation of the main regularities of origin, development and
movement of sediment transport in the lithodynamic systems is a task of the
ocean dynamics of the contact zone, which is a branch of marine physics or
geophysics in a broad sense.
Let us return to the description of the main tasks and concepts of the ocean
contact zone dynamics or lithodynamics of the local lithodynamic systems. The
construction of models of local systems should result in the expression of sediment
transport discharge. This expression should be given in a form, suitable for the
discharge under given conditions of the contact zone. These conditions include such
factors as the nature of the underlying surface, energy parameters and structure of
hydrodynamic field for hydrogenic processes, floor gradient and composition of the
bottom and moving sediment for suspension flows and gravitational displacements.
The next stage of the investigation of the contact zone lithodynamics is the
determination of the influence of unstable environment of the contact zone on
transport discharge. At this stage, the main concept of the lithodynamics of any
system arises, which is the discharge gradient. The value and sign of the gradient
determine the morphologic effect or system performance on the given area and
processes of sediment differentiation on the flow route according to the hydraulic
coarseness.
If a constant speed is maintained by exogenous forces in a flow, moving above
the washed-out floor, this flow becomes saturated with solid load over a part of its
route, and during subsequent motion, the interchange between the sediment and the
floor occurs, while the load, applied in the saturation area, remains constant.
However, even after the saturation the flow still consumes energy to overcome
resistance to its motion at a given speed to maintain the entire motion of the solid
load. When the energy supply to the flow decreases, the speed becomes slower,
negative discharge gradient develops, and a part of sediment is deposited simultaneously with its differentiation in accordance with the hydraulic coarseness. If the
energy decrease is smooth, deposition will proceed over some portion of the route
until the balance is gained between the consumed and received energies. If the
energy supply stops completely or decreases sharply, a local accumulation form
will result.
It should be noted that a quantitative solution, which requires the knowledge of
the flow discharge parameters, is possible only in rare cases, related to the dynamics
of the local systems. In the lithodynamics of the regional systems, it is possible to
122
R.D. Kosyan and B.V. Divinskiy