. EXAMPLES OF SECOND-CYCLE FORMS 209 



Most faulted structures are today probably in a later cycle of erosion 

 than the one introduced by the faulting. Hence although the space here 

 devoted to the forms developed in later cycles is less than that given to 

 the forms of the cycle introduced by faulting, the use of the terms chiefly 

 associated with later cycles, such as obsequent and resequent fault-line 

 scarps and subsequent fault-line valleys, ought probably to be more fre- 

 quent than that of terms associated with the cycle of faulting, such as 

 fault valleys, consequent scarps, and so on. 



Examples of second-cycle Forms on faulted Structures 



An admirable example of a submaturely dissected resequent fault scarp 

 is found where westward ascent is made from the broad plains of the 

 Limagne to the crystalline highlands of Auvergne in central France. 

 The scarp might well be taken, at first sight, to be consequent on fault- 

 ing; but a study of the lava-flows that cross it and their relation to the 

 lacustrine strata that once filled the Limagne graben will prove its rese- 

 quent origin. An equally good example is found in the western part of 

 the same crystalline highland, known as the Limousin, where it sud- 

 denly descends southwestward into the basin of Brives, that has been 

 excavated on weak strata which were brought down against the crystal- 

 lines by strong faulting, as described by Demangeon ('10). A third 

 example, this time of a maturely dissected obsequent scarp, is found in 

 the ascent on the northeast side of the excavated subsequent depression 

 in northwest France, known as the Pays de Bray, of which the geological 

 history has been studied out by Lapparent (79, 113—). The renewed 

 erosion in the second and third of these examples followed a late stage 

 of an earlier cycle at the beginning of or before which the faulting took 

 place. 



A remarkable group of escarpments following a series of east-west faults 

 occurs in central Sweden and is finely represented on the 1 : 100,000 map 

 of that country, sheets 55, 56, 65, 66, 73, 74. These escarpments have 

 been regarded as what are here called submature consequent fault scarps 

 by Gunnar Anderson ('03, 27-49) and S. De Geer (10, 34), but are to 

 my view ('12,169) better explained as submature resequent fault-line 

 scarps developed in a second cycle, following the old age of a previous 

 cycle; many subsequent fault-line valleys are associated with them. On 

 the other hand, Brogger ('86) has described some mature scarps in the 

 Christiania district which face the uplifted side of their fault-lines and 

 which would therefore here be called obsequent. They are probably due 

 to erosion in a later cycle of erosion than the one introduced by faulting. 



