It is commonly accepted that several processes come into play in the formation of the archaeological record, and often the challenge of reconstructing past human behaviors and activities is dependent on the interpretation of the sedimentary context of the archaeological remains. In archaeological sites, in addition to geogenic and biogenic depositional and post-depositional processes commonly referred to in geology, humans play important roles as well as agents of sedimentation and transformation of the sedimentary record. This Ph.D. thesis takes a geoarchaeological perspective on the study of archaeological sediments and features using micromorphology, or the microscopic study of soils and sediments, to reconstruct formation processes at Contrebandiers Cave, Morocco (Chapter 2), and to study anthropogenic-derived sediments associated with fire use at early anatomical Modern humans occupations in Africa (at Contrebandiers Cave - Chapter 3) and Neanderthal populations in Europe (Roc de Marsal Cave - Chapter 4). North Africa has several important, well-stratified archaeological sites that provide evidence for the understanding of early modern humans' adaptations and behavior. However, little is known on the formation processes and the degree of preservation of many of the archaeological assemblages there. In this thesis, the sedimentary history of Contrebandiers Cave is reconstructed taking into consideration the overall evolution of the cave's surroundings. The results show that gravity-driven and aeolian inputs contributed greatly for the fairly rapid fill of the cave during the last Interglacial (Marine Isotopic Stage 5). Since diagenesis played a minor role, the archaeological assemblages are mainly affected by mechanical disturbance related to bioturbation. The micromorphology study of fire residues showed that the combustion features from Contrebandiers Cave are poorly preserved, with common mechanical disturbance by biological activity, and the presence of natural features that might be mistaken as fire evidence. The displacement of some of the fire residues is, in addition, attributed to human action of ranking out hearth deposits. On the other hand, micromorphology observations of fire derived sediments at Roc de Marsal attest to the well-preserved nature of the hearths in this site, which suffered little or no post-depositional displacement. Despite this almost `pristine' preservation, the developed study highlights the difficulty of tracing past human activities in association with each of the identified hearths. Such results suggest that is often impossible to access the degree of contemporaneity between different combustion events and, consequently, to distinguish between temporally separated prehistoric occupations at an archaeological site.