Table 1.

Stratigraphic and archaeological summary of Nasera rockshelter. Bold values denote arbitrarily defined instances of major changes within each variable. n.a., not applicable; n.d., no data.

level	18–25	12–17	8/9–11	6/7	4/5	3b	3B	3A
industry	Kisele	Kisesle	Mumba	Nasera	Lemuta	Silale	Olmoti	Angata Kiti
technocomplex	MSA	MSA	MSA/LSA	MSA/LSA	early LSA	ceramic LSA + PN	ceramic LSA (Kansyore/Nderit)	PN (Narosura/Akira)
age estimate (ka)	56–73	56–73	50–56	25–37	16–24	8	5	2
accumulation span (kyr)	17	17	6	12	8	1	1	1
artefact volumetric density (artefacts m−3)	67.02	32.86	56.84	1031.89	2170.55	648.50	1808.24	484.67
artefact accumulation rate (artefacts m−3 kyr−1)	3.94	1.93	9.47	85.99	271.32	648.50	1808.24	484.67
retouched tool count	188	61	46	355	390	215	147	99
retouched tools : artefact volumetric density	2.81	1.86	0.81	0.34	0.18	0.33	0.08	0.20
local : non-local raw materials	5.45	4.5	6.33	23.72	8.07	18.95	12.54	6.28
debitage : non-local tools	76.98	26.33	27.93	144.09	155.04	131.46	105.61	36.03
local : non-local cores	3.7	3	29	23.74	11.56	27.33	19.3	3.82
local : non-local tools	3.35	1.03	2.07	4.55	4.17	6.68	4.25	1.54
occupation span index (OSI)	36.31	17.98	22.36	96.48	67	82.34	60.49	24.85
avg. non-bipolar core size (mm)	40.72	48.6	30.2	30.44	28.98	22.3	n.d.	26.68
avg. bipolar core size (mm)	26.23	28	20.6	24.94	24.08	20.6	n.d.	24.53
avg. point size (mm)	42.1	40.8	35.5	28.01	n.a.	31	n.a.	31
tip cross-sectional area (TCSA)	156.84	120.51	100.19	74.78	n.a.	103.16	n.a.	76.59
avg. endscraper length (mm)	31.03	34	29.2	26.3	24.21	18.6	31.1	31.1
retouched tool count	188	61	46	355	390	215	147	99
points (%)	13.3	18	4.3	14.6	0.3	0.5	0	1
backed microliths (%)	1.1	0	6.5	3.9	30.5	56.7	29.3	24.2
Levallois core (%)	9.7	14.3	16.7	11.9	6.3	0	0	0
bipolar core (%)	9.9	24	46.7	47.8	37.4	55.3	61.9	65.4
CA axis 1	n.d.	n.d.	0.47	0.17	−0.87	0.40	n.d.	1.75
CA axis 2	n.d.	n.d.	−2.17	−1.29	0.46	1.85	n.d.	0.47