Nonetheless, several pieces of evidence—many of which come from laboratory simulations of deep Earth conditions—have indicated mechanisms for the element's movement down into the lower mantle, as well as the forms that carbon takes at the extreme temperatures and pressures of this layer. Furthermore, techniques like seismology have led to greater understanding of the potential presence of carbon in the Earth's core. Studies of the composition of basaltic magma and the flux of carbon dioxide out of volcanoes reveals that the amount of carbon in the mantle is greater than that on the Earth's surface by a factor of one thousand.[2]