Internet Archaeol. Laurie. Methodology

The modern cockles were obtained from areas of the widest possible type of collection practices: a commercially exploited site in Wales, an undisturbed cockle population in Scotland and two recovering populations in Essex and Lincolnshire. It was thought that the differences in collection methods at the modern sites would provide contrasting age curves that may help to highlight changes in cockle exploitation through time. The result of the age curve analysis is given in section 3.2 (see Figures 11, 12, 13 and 14).

Each collector was asked to provide at least 25 cockle shells collected once per month for 24 consecutive months. A two-year period of collection was chosen in order to highlight any inter-year variability in growth patterns. Receipt of samples from all sites did not cover the full 24 months (see Table 1); however, enough months were covered to provide a good record of cockle size, age and growth patterns.

Table 1: The dates and number of cockle valves received from the modern British collection sites

Lincolnshire	Collection date	Number of valves received
Lincolnshire	Collection date	Left	Right
Friskney	17/02/2003	20	19
Butterwick and Wrangle	16/06/2003	33	32
Butterwick	11/08/2003	38	46
Butterwick and Wrangle	10/11/2003	39	40
Butterwick	08/12/2003	25	25
Total Number of Samples		155	162
Essex	Date of receipt	Number of valves received
Essex	Date of receipt	Left	Right
Buxey Sands	15/09/2003	25	25
	30/09/2003	25	25
	13/11/2003	28	28
	12/02/2004	21	21
	10/05/2004	25	25
	16/11/2004	26	26
Total number of samples		150	150
Wales	Date of receipt	Number of valves extracted
Wales	Date of receipt	Left	Right
Burry Inlet	14/02/2003	50	50
	19/03/2003	53	53
	12/05/2003	50	50
	25/07/2003	50	50
	18/09/2003	39	50
	03/10/2003	26	50
	08/11/2003	21	25
	10/12/2003	32	32
	12/01/2004	25	25
	02/02/2004	30	25
	08/03/2004	25	25
	06/04/2004	30	30
	25/06/2004	39	40
	20/07/2004	54	54
Total number of samples		524	559
Scotland	Collection date	Number of valves received
Scotland	Collection date	Left	Right
Mill Sand	28/02/2003	24	25
	24/03/2003	27	28
	30/04/2003	28	23
	31/05/2003	33	31
	30/06/2003	33	33
	31/07/2003	30	30
	31/08/2003	29	29
	28/09/2003	31	29
	28/10/2003	41	41
	26/11/2003	25	25
	07/12/2003	30	30
	07/03/2004	30	30
	25/04/2004	25	25
	30/05/2004	30	30
	30/06/2004	25	25
	21/08/2004	30	30
	15/09/2004	31	31
	17/10/2004	29	29
Total number of samples		531	524

Archaeological cockles were collected from the two Danish shell midden sites of Krabbesholm and Norsminde; see Figure 3 for the locations.

On receipt of the archaeological unsorted midden samples, they were dried in the laboratory and then sorted into mollusc species and other materials such as bone and pottery. The mollusc species were counted to provide a minimum number of individuals (MNI) using the undamaged apices of the gastropods and the undamaged hinges of the bivalves. All whole cockle valves were extracted and measured for height, width and length dimensions. The cockles were also aged using the external annual growth lines.

The modern cockles were also measured and aged. Suitable valves were then selected from both archaeological and modern collections for dissection and acetate peel manufacture; for numbers of valves used at each stage of analysis see Table 2.

Figure 3: Map showing the location of Krabbesholm and Norsminde midden sites in Denmark

Table 2: The number of modern and archaeological cockle valves used at different stages of analysis

Modern locations	Total number of samples	Number of valves measured and aged	Number of valves selected for acetate peels	Number of successful peels
Essex	300	300	60	27
Lincolnshire	317	317	50	34
Scotland	1055	1055	180	119
Wales	1073	1073	140	101
Totals	2745	2745	430	281

Archaeological locations	Total number of samples	Number of valves aged	Number of valves measured	Number of valves selected for acetate peels	Number of successful peels
Norsminde	2521	2511	2521	100	57
Krabbesholm 7737	432	372	432	69	42
Krabbesholm 7738	419	405	419	55	31
Totals	3372	3288	3372	224	130

2. Methodology