1) Depth important to farmers 
The M240 is a belt-fed 7.62 mm NATO medium machine gun, based on the FN MAG. It has been used by the United States Armed Forces since the end of the 20th century, and is also used by other NATO forces. Though not the lightest medium machine gun, it is highly regarded for reliability, and the firearm`s standardization with those of other NATO alli....
The maximum depth that frost can be expected to penetrate into the ground.
The depth of frost penetration in soil. This depth varies in different parts of the country. Footings should be placed below this depth to prevent movement. 
the maximum depth at which soil is frozen. · the lower limit of permafrost. Cf. permafrost table.