As the topography varies, the column of rock thins and thickens; this changes the gravity field.
Changes in rock type, hence rock density, cause variations in the gravity field.
The Earth's surface varies: we have mountains and valleys to wide plains and ocean trenches. |
To understand anomalies, let's assume that the Earth is completely smooth and featureless. Some regions of the planet—such as mountains—rise above the assumed surface creating a positive anomaly. Red-yellow areas show where these anomalies exist. Some regions of the planet—such as oceans—sink below the assumed surface creating a negative anomaly. Blue-green areas show where these anomalies exist. |