Your essay should be composed of sustained paragraphs, rather than short, extended bullet points. In principle, each paragraph should have a clearly defined theme: it is thus a discrete, internally cohesive entity within a greater whole. The first line of the paragraph should outline that theme; the last line forms the link to the next paragraph (thus ensuring that your argument flows). It is acceptable (although rare) to use section headings in physical geography essays; if used well, they can make the structure of your argument absolutely explicit.
You should arrange your argument in sustained paragraphs, rather than extended bullet points. Each paragraph should deal with a single, well-defined topic.
The following text is example of extreme disaggregation. These three paragraphs should be combined into a single paragraph with the topic ‘spatial scale’:
Spatial scales often relate closely to temporal scales. Temporal extent can be split into three categories; steady time, graded time, and cyclic time (Chorley et al, 1984). Steady time is used in relation to short time frames and generally encompasses small scale features such as a hill slope. At this time-scale only processes such as surface weathering and infiltration rates would be visible factors.
Graded time is generally used in relation to processes which extend over slightly larger areas, for example a catchment area. Steady equilibriums can be established at this scale as processes are more continuous. At this time-scale there are many factors visibly affecting sediment yield including geology, climate, vegetation cover, and topography.
Cyclic time is used in relation to large scale and continuous processes. Factors affecting these processes include; initial relief, rock structure, and climate zones. These processes have long relaxation times, so adjustments of the landscape caused by changes take longer to occur than if more rapidly occurring processes change (Chorley et al, 1984).
The first line of the paragraph should set out the topic to be covered. The first line of the previous extract actually does this very effectively.
The following excerpt is less successful. The author starts off by talking about underlying geological conditions, but then immediately talks about water shortages, before switching to human disturbance.
Underlying geological conditions have an influence on the slope, aspect and mineral content of the soil, all of which are crucial for determining the type and density of vegetation in a certain region. Water shortages prompt the growth of less dense vegetation which thus intercepts less of the available light. This wastage of solar radiation is the main cause of low productivity in many arid areas, rather than the reduced synthetic rate of the droughted [sic] plants, equally, in later successional forests net primary productivity declines. Human disturbance can impact incisively upon net primary productivity, resulting in changes in resource supply and Leaf Area Index. Forest net primary productivity frequently increases after disturbance and until the canopy closes and the available light is fully used (Ryan et al. 1997).
Contrast the previous paragraph with this one from the same essay:
Carbon dioxide plays a fundamental role in the micro-scale photosynthesis reaction but also spans the scale of influence to have global impact. Global warming is expected to prompt greater carbon dioxide concentrations in the atmosphere which will enable global net primary productivity to increase. A recent modelling exercise indicated that a doubling of atmospheric CO2 would stimulate an increase in net primary productivity of 10-30%. Trees use C3 metabolism and their rates are limited by the current atmospheric carbon dioxide concentration of 370 ppm thus stimulation of photosynthesis by carbon dioxide will increase forest net primary productivity.
The final sentence of the paragraph is a good way of forming a bridge to the next paragraph. For example:
…Community structure is so complex to measure that the over-simplified relationship suggested by equilibrium theory is insufficient to explain the interactions between mutualists, dependents, and specialist predators in the trophic structure.
As a result, recent competing models or modifications of equilibrium theory have emerged…