A study on the relation between stratigraphical succession of Kwanto “loam” (volcanic ash beds) and its hardness, especially consolidated dark blue part of the volcanic ash, are made at Oba district, western part of Fujisawa city. The Kwanto “loam” are divided into Shimosueyoshi loam and Younger loams (Musashino loam and Tachikawa loam are put together in this paper), and the following five terraces are distinguished in the area studied; namely, Kaza, Golf-jo, Hiko-ja, Matano and Hikiji-gawa terraces. Many pumice or scoria seams, which are of for stratigraphic correlation of Kwanta “loam” at each outcrops and bore-holes, are summarized throughout the area, among them, Tokyo pumice, Miura pumice, An-shin pumice, Fujisawa pumice, etc. are remarkable. Results of standard penetration test (N-value diagram) are compeared with the bore-hole stratigraphical succession at each boring sites, by observation of core-samples with naked eyes.As results, the followings are concluded;1) From the results of standard penetration test, the Kwanta “loam” is subdivided into four groups:Group I: N≅ 3-4Group II: N≅ 7-8Group III: N≅ 11-16Group IV: N≅ 20 or moreAmong the groups, III and IV are consolidated volcanic ash under visual observation, which is dark bluish in color.2) Distinct difference of N-value are found between Shimosueyoshi loam and Younger loams. Shimosueyoshi loam is more solidified throughout all bore-hole successions.3) Younger loams, covering the higher terrace, is more solidified than that of the lower terrace.4) Consolidated dark blue part of Kwanto “loam” are, in most cases, found upwards or around the pumice seams. On the contrary, pumice or scoria seams are less solidified than the surrounding volcanic ash beds.5) Solidification of volcanic ash is presumably caused by geochemical reaction between volcanic ash and ground water which are contained or permiate into the pore space of the loam beds.