- [Ali] We are in the Sacramento Mountains in New Mexico and what we've got right in front of us, right there is a large Phylloid Algal mound, and what I'd like you to focus on are the strata onlapping onto the mound. And this is something you not only get with Phylloid Algal mounds you'll get an onlap against any sort of carbonated build up, including modern coral reefs. And especially if you're looking at seismic data, the mound or any sort of build up is going to be seismically transparent with onlapping reflections onto it.