== Definition of lithosphere asthenosphere boundary == 

 "Lithosphere" has the potential to become a really great article, but it is currently missing a few key topics. The article would benefit from discussions of the effective elastic thickness and how it relates to lithospheric thickness (Burov and Diament, 1995), rheological models of the lithosphere (i.e., yield strength envelopes)(Goetze and Evans, 1979), and the observation that the equation given for lithospheric thickness does not work for lithosphere older than ~80 Ma, possibly due to small-scale convection (Parsons and McKenzie, 1978). 

 However, I think this article would benefit most from a discussion of the different ways in which the base of the lithosphere is defined. Right now the article suggests that the base of the lithosphere is defined as the brittle-ductile transition (BDT) in olivine, following the mechanical-boundary layer definition of Parsons and McKenzie (1978). However, several other definitions exist including 1) the crust and portion of the mantle which mainly transports heat through conduction rather than convection (i.e., a thermal boundary layer), 2) a rheological boundary defined by compositional differences (e.g., water and/or melt content; this is becoming increasingly well received and should be mentioned), and 3) the seismically fast, elastically anisotropic lid (i.e., seismic lithosphere). An excellent review is given by Fischer et al. (Annual Reviews of Earth and Planetary Sciences, 2010). 

 Although the definition currently provided is worth mentioning, statements such as "the lithosphere remains rigid for very long periods of geologic time in which it deforms elastically and through brittle failure" reflect the outdated perspective of the article as written.