There isn't a single machine that directly "records" the movement of rocks within the Earth's crust. Instead, scientists use a combination of techniques and instruments to study these movements, which are incredibly slow and complex. Here's a breakdown:

* GPS (Global Positioning System): GPS stations placed on the Earth's surface can measure very precise changes in position over time. This data reveals how tectonic plates are moving and deforming.

* Geodetic measurements: Techniques like Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) can track the movement of the Earth's crust with incredible accuracy, revealing tectonic activity.

* Seismometers: While primarily used to detect earthquakes, seismometers also record the constant vibration of the Earth's crust. These vibrations provide clues about the movement and stresses within the Earth.

* Strainmeters: These instruments measure subtle changes in the shape and size of the Earth's crust, providing insight into the forces that cause earthquakes and plate movement.

* Magnetometers: These instruments measure changes in the Earth's magnetic field, which can be influenced by the movement of tectonic plates.

It's important to note that the movement of rocks within the Earth's crust happens very slowly, often over millions of years. Therefore, scientists rely on a combination of these instruments and data analysis to understand this process.