A brief historical review of the development of crustal seismic studies is presented including the importance of the Mohorovičić (Moho) Discontinuity and the basic composition of the earth's crust. The essential elements of Wide-Aperture Reflection and Refraction Seismics (WARRS) using wide-angle reflection and refracted diving waves are discussed with an explanation of how they can provide both P and S wave velocity models of the crust.

A discussion of the instrumentation used for collecting crustal seismic data both on- and off-shore is followed by four case studies from different environments. These demonstrate how crustal seismic data can be used to provide a regional understanding of the physical properties of the crust and the regional geology of the basin and its importance in the early exploration stage of the exploration and production process. The importance of integrating the crustal seismic data with other geophysical data to obtain an optimum geophysical model is stressed. This leads to a better understanding of the key geological processes that assists the exploration strategy. A brief discussion of the costs involved in acquiring crustal seismic data is presented.

Introduction

It has often been noted that female primates tend to have extended mating periods in their ovarian cycles, tend to mate polyandrously and also tend to mate during pregnancy (cf. Hrdy 1979; Hrdy & Whitten 1987). Since females in species vulnerable to infanticide show these features to a greater extent, this behavior was interpreted as serving to confuse paternity (cf. van Schaik et al. 1999; van Noordwijk & van Schaik, Chapter 14). The extent to which such mating tactics succeed in confusing paternity depends on the outcome of an “arms race” between males and females concerning the amount of information on paternity available to males. In order to examine more closely the claim that sexual behavior in primates serves at least in part to reduce infanticide risk, we must examine the physiological basis for paternity confusion, as well as for its complement, paternity concentration. Since ovarian cycles vary considerably in detail among taxa (e.g., Short 1984), we limit this examination to primates, the best-known order in this respect. We ask therefore how the ovarian cycles of female primates are organized in relation to the need for strategies to reduce infanticide risk. Two features are examined in particular which we will argue are related to the benefits to females of unpredictability in the timing of ovulation: (1) the large variance in the length of the preovulatory or follicular phase both within and between individuals, and (2) interspecific variation in the mean length of the follicular phase.