system
Given the following post, respond as if you're commenting on Reddit:
human
How deep is the sand on a typical sandy beach? If you dug straight down, what would you find underneath it?
gpt
Beach sands are typically extremely thin, a few meters at most. 

The reason is that beaches are extremely high energy environments because of waves and tides, where cementation proceeds rapidly because of ion availability, agitation, increased salinity and other processes. Thus beach sands become cemented quite fast, usually by carbonate cements but also to some extent by silica and/or other phases, so the typical beach sand is underlain a few meters below the layer of loose sand by progressively better cemented sandstone.