GUATEMALA AND THE HIGHEST NATIVE AMERICAN CIVILIZATION. 213 



ments. On the lower Motagua River, in the wet forested country, the terraces are only 

 slightly developed, but may be seen near the notable ruins of Quirigua and elsewhere; 

 on the dry middle course of the river, from Zacapa upward, they are highly developed; 

 and in the moderately watered regions of the upper course they are also well developed. 

 This is likewise the case along the only two main tributaries which I saw, the Copan and 

 Chiquimula branches, which join the main river at Zacapa. On the upper river, where 

 it is crossed by the road from S. Toma de Chichestenango to S. Cruz de Quiche, there is 

 convincing proof that the terrace-making process consisted of both erosion and deposition. 

 Because of the change in the relative positions of the main stream and a tributary, one can 

 see an old channel which was first excavated and then filled with gravel to a depth of 40 

 to 50 feet and perhaps more. The top of this gravel corresponds with a well-developed 

 terrace. 



The Motagua River, flowing from high, dry regions through alternate gorges and broad 

 valleys, is the kind of stream that might be expected to have terraces of climatic origin. 

 Its little neighbor, the Santa Toma, on the other hand, is of quite a different nature. 

 It is a short, insignificant stream running down from the eastern end of the Sierra de las 

 Minas, between the large Motagua River on the south and the Rio Dolce on the north. 

 Its entire course appears from the maps to be not over 30 miles, and all of it apparently 

 hes among dense vegetation. In this region, in contrast with the j'outhful coastal plain 

 of Yucatan, the last main movement of the land seems to have been downward, so that 

 the inner corner of the Gulf of Honduras, near Puerto Barrios and Livingstone, presents 

 a strikingly bold, indented coast line with isolated islands and deep inlets. This movement, 

 however, occurred long ago and since its completion a long period of comparative stability 

 has allowed large deltas to be formed. In ascending the Santa Toma River one traverses 

 a delta for perhaps 5 miles, first through mangrove swamps and then through the ordinary, 

 dense tropical forest. A small terrace appears after one is well within the sohd portion of 

 the delta; farther inland it becomes higher, and where the delta joins the hilly old land at 

 least four terraces are well developed. The full development of the delta and the apparent 

 absence of any signs of recent upheaval of the land agree with the lines of evidence already 

 cited in other chapters in indicating a chmatic rather than tectonic origin of the terraces. 

 If this be correct, the terraces of the Santa Toma are particularly significant because the 

 whole course of the river Ues in a region of abundant vegetation. This suggests that in 

 tropical regions, unlike those of the temperate zone, changes of climate have appreciably 

 influenced the amount of vegetation, or at least the rate of erosion, not only in arid regions 

 but even where dense forests prevail. 



If the terraces are really of climatic origin important consequences follow when we 

 investigate their relation to ruins. Among the greatest of the ruins of Maya land are 

 those of Copan on the Copan tributary of the Motagua, just over the Guatemalan border 

 in northern Honduras. Beginning at the wretched little modern village of Copan, the ruins 

 extend up the right bank of the river for at least 1.5 miles, and in the last three-quarters of 

 a mile of that distance the ancient walls are practically continuous. At the southwestern 

 end of the main ruins the walls of the chief citadel, or temple, rise directly from the river, 

 which is almost undermining them and may soon cause their fall. The relation of the wall 

 to the deposits of the river is shown in the profile and cross-section of figure 73, and in the 

 accompanying description. It is also illustrated in Plate 10, b, page 211. 



Before the full meaning of the diagram is explained, attention should be called to 

 figure 74. From this it will be seen that the ruins stand upon a terrace about 18 feet above 

 the present low-water level. They follow this very closely and were evidently built along it. 

 Just below it there Ues another terrace, 12 feet above low-water level, and to-day quite 

 as good a place for houses as is the upper terrace. The fact that no trace of ruins is found 

 upon it and the conditions of deposition shown in figure 73 seem to indicate that when 



