- Between 1535 and 1544 (white squares) grants for ranches were on gentle slopes, low elevation slopes that faced south. Low elevation and southern-facing slope are good factors for agriculture, but also good factors for bountiful pasture, so the land-grantees were getting prime land at this time.
- Between 1559 and 1568 (blue squares) the grants were on the highest average elevations with the steepest slopes. This, explains Hunter was because of policy change by the Viceroyalty: they were now attempting to protect the indigenous peoples' crops from cattle. Ranches were required to be certain distance away from indigenous pueblos and their corresponding agricultural zones. Indigenous nobility were also awarded land during this time.
- Between 1577 and 1586 (orange squares) ranches were granted on slopes that held evidence of terrace farming. Hunter explains that this is because the native populations had been hit intensely by disease and were shrinking, abandoning their outlying and least productive terrace farms.
- Between 1589 and 1596 (red squares) the government continued to grant land that was formerly used for agricultural terraces. Hunter explains that this is the result of a policy called congregación, of the forced grouping of Native peoples into compact settlements to "facilitate religious conversion." This left much land uncultivated as it was now too far away from the settlements, so the abandoned land was used for more grant land.
- Between 1600 and 1610 (brown squares), the land grants describe a degraded landscape of eroded topsoil and vanishing groundwater. Hunter proposes that this is the result of overgrazing and the abandonment of agricultural practices on the terraces. (combined with climate changes and deforestation of some areas.)
GIS enabled the land grants, historical documents, to be supplemented with on-site data about elevation, slope, and slope direction that led to Hunter's conclusions about what types of land were developed during which time period. It also shows how connected human history is to the natural features it played out on.
I have acted with honesty and integrity in producing this work and am unaware of anyone who has not.
Hunter, R. (2014). Land use change in New Spain: A three-dimensional historical GIS analysis. The Professional Geographer, 66(2), 260-273.