Contact
Contact turns up in 3 fields: hydrography, mining, shop slang. Here is what it means to the people in each one.
Contact in hydrography
A target picked out of side-scan or multibeam data that may be an object worth investigating.
A possible object identified in sonar data and logged with a number, position, dimensions and an image. Side-scan contacts are measured from their shadows, correlated between overlapping lines and compared with multibeam, then classed as significant, insignificant or false. Significant contacts are developed for least depth; a contact seen on only one line with no shadow is usually written off as noise.
"Contact 27 shows on both lines with a 1.5 metre shadow, flag it for development."
Contact in mining
The boundary surface where two different types of rock touch each other.
The physical plane or zone separating two adjacent rock units of different types or ages. Contacts can be depositional, intrusive, or structural, such as a fault plane. Mapping these boundaries is fundamental in exploration geology, as mineral deposits frequently concentrate right at the contact zone due to fluid flow or chemical reactions between the contrasting rocks.
"The gold grades spike right at the contact between the basalt and the metasediment."
Contact in shop slang
The exact physical point or moment when a cutting tool, probe, or moving component touches the workpiece.
The initial physical engagement between a machine tool and the raw material being processed. Operators carefully monitor this moment to establish a zero reference point before beginning a heavy cut or automated sequence. A harsh or unexpected engagement can shatter carbide inserts, ruin the surface finish, or throw the machine out of alignment.
"Bring the spindle down slowly in manual mode until you get contact with the top of the block."