In a blind zone, the geophone cannot detect the seisdmic refraction.

Mud rotary drilling belongs to _____ type of boring method.

The type of boring, used for making deep excavations is _____

In open drive samples, the tube is split into two parts.

The cone test is very useful in ______

The type of boring method that can be used for both rock and soils are ____

Exploratory borings in general exploration is carried out by using _______

The sampler is driven through ________ as seating drive.